A reappraisal ofPelargonium sect.Ligularia (Geraniaceae)

Plant and Evolution .

P1. Syst. Evol. 179:257-276 (1992)

....

Systematlcs © Springer-Verlag 1992 Printed in Austria

A reappraisal of Pelargonium sect. Ligularia

( Geraniaceae) FOCKE ALBERS, MARY GIBBY, and MATH1LDE AUSTMANN Received July 30, 1991

Key words: Angiosperms, Geraniaceae, Pelargonium. - Chromosome numbers, karyotypes, hybridization, taxonomy. Abstract: A study of 33 species of Pelargonium sect.

Ligulariareveals four basic chromosome numbers, x = 8, 9, 10, and 11, and variation in chromosome size. From evidence of karyology and hybridization attempts, proposals are made to divide the section into smaller groups and to transfer some species to other sections. The genus Pelargonium is largely southern African in distribution, and comprises at least 250 species, at present arranged in 17 sections (KNuTH 1912, VAN DER WALT & VORSTER 1983, DREYER & al., unpubl.). Detailed karyological studies have been m a d e in several sections; some have proved to be cytologically uniform, for example, sect. Pelargonium (x = 11, small chromosomes; AL~ERS & VAN DER WALT 1984), the revised sectt. Glaucophyllum and Cortusina s. str. (x = 11, small chromosomes; VANDER WALT & al. 1990 a; DREYER & al., unpubl.), sectt. Ciconium and Dibrachya (x = 9, m e d i u m sized chromosomes; GIBBY & al. 1990), and new sect. Reniformia ( x = 8 , m e d i u m sized chromosomes; DREYER & al., unp u b l . ) - w h e r e a s sect. Jenkinsonia shows variation in basic c h r o m o s o m e n u m b e r (x = 9, 11, 17, m e d i u m sized chromosomes; GmBY & al. 1990), and sect. Eumorpha has variation in both c h r o m o s o m e size and basic c h r o m o s o m e n u m b e r (x = 4, 8, 9, 11, 17, small, m e d i u m sized and large chromosomes; GI~BY & WESTFOLD 1986, GIBBY 1990). Variation in basic c h r o m o s o m e n u m b e r within a section m a y indicate a polyphyletic origin for the section, and hence an artificial classification, as has been suggested for sectt. Eumorpha and Jenkinsonia (GIBBY & WESTFOLD 1986, GIBer & al. 1990), and the species of sect. Eumorpha with x = 11 have n o w been transferred to sect. Glaucophyllum (VAN DER WALT & al. 1990 a). However, change in base n u m b e r m a y be of relatively recent origin, as appears to be the case in P. alchemilloides (L.) L'H~RIT. (sect. Eumorpha), where two basic c h r o m o s o m e numbers are found within one species (GmBY & WESTFOLD 1986, GIBBY 1990). In fact, VAN DER WALT & VORSTER (1988) n o w include sectt. Dibrachya and Eumorpha in sect. Ciconium. The species of sect. Ligularia as circumscribed by KNUTH (1912) are of a diverse

258

F. ALBERS& al.:

morphology - in habit, in floral and in vegetative structures. They extend throughout Namibia and South Africa, with the exception of the lowveld of Transvaal and Natal, under a wide range of environmental conditions, which is rather unusual in comparison with other sections of Pelargonium. Most of the species are illustrated and described in VAN DER WALT (1977), VAN DER WALT & VORSTER (1981, 1988). A karyological study has been made of material of known wild origin of 33 species belonging to the section, to investigate relationships of species within the section, or with species from other sections of the genus Pelargonium. In addition, attempts have been made to hybridize species of sect. Ligularia with species from other sections to attempt to identify any close relationships. Material and methods

Most of the living material has been provided by Prof. J. J. A. VANDEk WALT and Dr P. VORSTERat the University of Stellenbosch, Republic of South Africa, with a few specimens collected by the authors or others. The species of sect. Ligularia that have been studied are listed in Table 1 together with authority, origin and Stellenbosch University or other accession number; most herbarium vouchers are at STEU (STEU numbers), others are at BM or Mfinster. Methods used were those described in GIBBY& al. 1990. Results

Karyology. Chromosome numbers from accessions of known wild origin of 33 species are summarised in Table 1. There is remarkable diversity in chromosome number, with four basic numbers reported, x = 8, 9, 10, and 11, and also a range in chromosome size. Three species have x = 8; P. exstipulatum and P. ionidiflorum (Fig. 1) are diploids, whereas for P. abrotanifolium both diploids and tetraploids have been found. Previous counts for P. abrotanifolium and P. ionidiflorum by DAKER (1969) are confirmed. Chromosome size in the three species is similar. Ten species have x = 9; six are d i p l o i d - P , aridum (Fig. 2) (this confirms the report of this species by DAKER 1969), P. barklyi (Fig. 3) (previously reported as 2 n = 18 by Yu & HORN 1988 but included in the sect. Hoarea), P. dolomiticum (Fig. 4), P. trifidum (previously reported by GI~BY in VORSTER 1986, and under the name P.fragile by Yu & HORN 1988), P. griseum (Fig. 5) and P. tragacanthoides. The three tetraploid species are P. divisifolium (previously reported as 2 n = 44 under the name P. artimisaefolium by Yu 1985), P. plurisectum (Fig. 6) and P. tenuicaule, and for one species, P. articulatum, both diploid and tetraploid counts have been obtained. There is a little variation in chromosome size amongst these species with x = 9, but in general the chromosomes are larger than those found in the species with x = 8 (compare Fig. 1 with Figs. 2 - 5). Five species have x = 10, P. grandicatcaratum, for which tetraploid and hexaploid counts (Fig. 7) have been obtained, P. karooicum with diploid, tetraploid (Fig. 8) and hexaploid counts, and two diploid species, P. otaviense (Fig. 9) and P. spinosum (Fig. 10); this latter species is included here because of its affinities with P. otaviense (see VAN DER WALT & al. 1990a), although it was previously included in sect. Glaucophyllum by KNUTH. The chromosomes of all these four species are similar in size. P. setulosum, a tetraploid with 2 n = 4 0 (Figs. 11, 12), has smaller chromosomes (compare Fig. 12 with Fig. 9).

Pelargonium sect. Ligularia

259

Table 1. Pelargonium spp. investigated with authority, origin, accession number, and chromosome numbers Origin

Accession number (STEU no.)

Chromosome number (2 n)/ metaphase 1

681 784 1059 1744 2581

16 32 32 32 32

Basic chromosome number x = 8 P. abrotanifolium (L. f.) JACQ.

Cape, Cape, Cape, Cape, Cape,

P. exstipulatum (CAV.) L'H~;RIT.

Cape, Herbertsdale

1656

16

P. ionidiflorum (EcKL. & ZEYH.) STEUD.

Cape, KingWilliamstown Cape, Grahamstown Cape, Gt. Fish River Pass

1874 1888 2181

16 16 16

Graaff-Reinet Malgas Riversdale Nieuwoudtville Laingsburg

Basic chromosome number x = 9 P. aridum R. A. DYER

Cape, Cape, Cape, Cape,

Cradock Middelburg Middelburg Cookhouse

1843 1847 3269 3272

18 18 18 18

P. articulatum (CAv.) WILLD.

Cape, Cape, Cape, Cape, Cape,

Nieuwoudtville Nougaspoort Ceres Matjiesfontein Matjiesfontein

1571 2761 G&C 241 UM 297 UM 626

36 36 36 18 18

P. barklyi SCOTT

Cape, Studer's Pass Cape, Kamiesberg Pass

2816 3325

18 18

Cape, Botterkloof Pass Cape, Riviersonderend Mts Cape, Greyton

1589 2978 3379

36 36 36

Transvaal, Pelgrimsrus

3082

18

P. griseum KNUTH

Cape, Oudeberg Cape, Andriesberg

2832 2838

18 18

P. pIurisectum SALTER

Cape, Stellenbosch Cape, Stellenbosch

2906 MG 20

36 36/18II

P. tenuicaule KNUTH

Namibia, Namuskluft

3061

36

P. trifidum JACQ.

Cape, Cape, Cape, Cape, Cape,

742 1611 2107 2111 2435 2730

18 18 18 18/9II 18/9II 18

ELLIOT

P. divisifolium VORSTER

P. dolomiticum KNUTH ex ENGL.

Worcester Matjesfontein Saffraanpoort George Worcester, Karoo B.G.

F. ALBERS&al.:

260 Table 1 (continued)

P. tragacanthoides BURCH.

Basic chromosome number x

=

Origin

Accession number (STEU no.)

Chromosome number (2 n)/ metaphase 1

Cape, Cradock Cape, Cradock Cape, Middelburg

1728 1843 1849

18 18 18

10

P. grandicalcaratum KNUTH

Cape, Studer's Pass Cape, Garies Cape, Garies Cape, Botterkloof Namibia, Schakalsberge Namibia, MacMillans Pass, Rosh Pinah

759 1513 1515 2055 2157 LAVP 19018

40 40 40 58 60 c. 60

P. karooicum COMPTON & BARNES

Cape, Cape, Cape, Cape,

621 622 1487 1524

40 20, 40 60 20

P. otaviense KNUTH

Namibia, Namib Desert Park Namibia, Elandshoek Namibia, Omaruru River

943 2201 2202

20 20/10II 20

P. spinosum WILED.

Cape, Richtersveld Cape, Goodhouse Cape, Numiesberge Cape, Springbok Namibia, Rosh Pinah

619 1357 2087 2097 AL&UM 67

20 20 20 20/10II 20

P. setulosum TURCZ.

Cape, Cape, Cape, Cape,

2477 GBB 388 3888 3889

c. 40 40/20II 20II 20II

Cape, Tulbagh Cape, Gt. Winterhoek, Kliphuis Cape, Gydopas

1937 2458

22 22

3574

44

Cape, Cape, Cape, Cape, Cape,

651 657 3983 634 MGV 2128

22 22 22 22 22

1738 1889

22/1111 22

Vrendendal Sannagas Bidouw Valley Wallekraal

Houwhoek Pass Macgregor Tygerhoek Macgregor

Basic chromosome number x = 11 P. alpinum Ec1~t. & ZEYH.

P. crassipes HARV.

P. desertorum VORSTER P. exhibens VORST~R

Lutzville Piketberg Brandseberg Richtersveld Richtersveld

Cape, Graaff-Reinet Cape, Grahamstown

Pelargonium sect. Ligularia

261

Table 1 (continued) Origin

Accession number (STEU no.)

Chromosome number (2 n)/ metaphase l

Cape, Yzerfontein s. loc. Cape, Leipoldtville Cape, Langvlei Mts ,Cape, Elandsbaai Cape, Alexander Bay Cape, Vrendendal

482 906 1026 3067 G&C 33 K1347 AL 2093

22 22 22 22 22 22 22

P. hirtum (BUI~Mf.) JACQ.

Cape, Lion's Head no data Cape, Tinie Versveld Reserve

550 950 1817

22 22 22

P. hystrix HARV.

Cape, Karoopoort no data

2994 ES 666

22 22

G&C 116 3282

22 22

P. fulgidum (L.) L'HI~RIT.

P. mollicomum FOURCADE Cape, Alexandria Cape, Grahamstown

807 870

22 22

P. oreophilum SCHLTR.

Cape, Pakhuis Pass Cape, Agter-Witzenberg

P. pulchellum SIMS

Cape, Cape, Cape, Cape, Cape,

Sannagas Kamieskroon Steinkopf Spektakel Pass Sannagas

654 1545 1567 2067 2969

22 22/1 lII 22 22 22

P. sericifolium J. J. A. v. D. WALT

Namibia, Rosh Pinah Cape, Spektakel Pass Cape, Steinkopf

916 2068 2369

22 22 22

P. stipulaceum (L. f.) WILLD.

Cape, Cape, Cape, Cape,

1600 1621 1949 2813

22 22 22 22

P. torulosum E. M. MARAlS

Cape, Klipplaat, Sutherland

3665

22/11II

P. worcesterae KNUTH

Cape, Cradock

3975

22/11II

P. xerophyton SCHLTR.

Cape, Konkypberg Namibia, Aus Cape, Kubus Cape, Hellskloof Cape, Wuppertal, Island Forestry Station Cape, Studer's Pass Namibia, Witputz Namibia, Rosh Pinah Cape, Studer's Pass Namibia, Rosh Pinah Namibia, Rosh Pinah

909 910 2086 2089 2098

44/22II 44 44 44 44

2813 2937 2944 2995 AI&UM 83 AI&UM 84

22 22/11II 22/11 II 22 22 22

ex KNUTH

Laingsburg Matjesfontein Keurboomsfontein Kamiesberg

262

F. AI~BERS& al.:

Figs. 1 - 6. Chromosomes ofPelargonium spp.; bar: 10 gin. - Fig. 1. P. ionidiflorum STEU 1874, mitosis, 2 n = 16. - Fig. 2. P. aridum STEU 1847, mitosis, 2 n = 18. - Fig. 3. P. barklyi STEU 2816, mitosis, 2 n = 18. - Fig. 4. P. dolomiticum STEU 3082, mitosis, 2 n = 18. - Fig. 5. P. griseum STEU 2838, mitosis, 2 n = 18. - Fig. 6. P. plurisectum MG 20, meiosis, 18 bivalents

Fifteen species have x = 11 and all are diploid with the exception of P. alpinum (Fig. 13) and P. xerophyton where diploids (Fig. 14) and tetraploids are found. Earlier reports of 2 n = 22 for P. exhibens (Fig. 15) (GIBBY in VORSTER 1986) and P. stipulaceum (Yv & HoRN 1988) are confirmed, but Y v & HoRN (1988) reported 2 n = 44 for P. hirtum, whereas the three accessions studied here were all found to be diploid (Fig. 16). It can be seen from comparison of meiosis in P. xerophyton (Fig. 14) with P. exhibens (Fig. 15) and P. torulosum (Fig. 17), and mitosis in P. alpinum (Fig. 13) with P. crassipes (Fig. 18), P. hystrix (Fig. 19), and P. worcesterae (Fig. 20), that there is considerable variation in chromosome size amongst these

Pelargonium sect. Ligularia

263

Figs. 7 - 12. Chromosomes of Pelargonium spp.; bar: l0 gin. - Fig. 7. P. grandicalcaratum, STEU 2157, mitosis, 2 n = 60° - Fig. 8. P. karooicum S T E U 622, mitosis, 2 n = 40. Fig. 9. P. otaviense S T E U 2201, mitosis, 2 n = 20. - Fig. 10. P. spinosum S T E U 2097, meiosis, 10 bivalents. - Fig. 11. P. setulosum GBB 388, meiosis, 20 bivalents. - Fig. 12. P. setulosum S T E U 2477, mitosis, 2 n = c. 40

species w i t h x = 11. A l t h o u g h at this stage we h a v e n o t m a d e a c c u r a t e m e a s u r e m e n t s o f this v a r i a t i o n f o r all the species, we c a n d i f f e r e n t i a t e three g r o u p s o f species o n

264

F. ALBZRS & al.:

Figs. 1 3 - 20. C h r o m o s o m e s of Pelargonium spp.; bar: 10 pro. - Fig. 13. P. alpinum S T E U 3574, mitosis, 2 n = 44. - Fig. 14. P. xerophyton S T E U 2944, meiosis, 11 bivalents. Fig. 15. P. exhibens S T E U 1738, meiosis, 11 bivalents. - Fig. 16. P. hirtum S T E U 550, mitosis, 2 n = 22. - Fig. 17. P. torulosum S T E U 3665, meiosis, 11 bivalents. - Fig. 18. P. crassipes S T E U 657, mitosis, 2 n = 22. - Fig. 19. P. hystrix S T E U 2994, mitosis, 2 n = 22. - Fig. 20. P. worcesterae S T E U 3975, mitosis, 2 n = 22

Pelargonium sect. Ligularia

265

chromosome size-small, medium, and large. P. alpinum, P. desertorum, and P. xerophyton have small chromosomes, P. crassipes, P. fulgidum, P. hirtum, P. hystrix, P. oreophilum, P. pulchellum, P. sericifoIium, P. stipulaceum, and P. torulosum have medium sized chromosomes, and P. exhibens, P. mollicomum, and P. worcesterae have large chromosomes. Hybrids. Attempts to hybridize species of sect. Ligularia with those from other sections are summarized in Table 2. Many of the attempts proved to be unsuccessful, and F 1 hybrids were obtained only for three crosses involving sect. Reniformia [P. extipulatum x p. dichondrifolium DC., P. ionidiflorum x p. odoratissimum (L.) L'H~r~IT. and P. abrotanifolium x p. sidoides DC.], one cross with sect. Glaucophyllum [P.fulgidum x p. grandiflorum (A~DR.) W~LLD.] and one cross with sect. Pelargonium, [P. englerianum KNUTH X p. fulgidum]. For several crosses inviable seeds were obtained (+ in Table 2). F 1 hybrids involving species of sect. Ligularia have been synthesized by other workers. In the early 19th Century there was great enthusiasm for hybridization in Pelargonium by many horticulturalists, and this was well documented by SWEET

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7

30 ~ I 4-----

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_-+-

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--~__

14° I

10 °

12 °

14 °

km 100

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16 °

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100 I

18 °

200 I

300 I

20':'

400 I

500 I

22 °

600 I

24 °

700 I

800

26 °

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Fig. 21. Distribution in southern Africa of species of Pelargonium sect. Ligu/aria with x = 11 (see also Table 4 and page # 273): • small chromosomes (p. xerophyton, P. desertorum), 41, small chromosomes (P. alpinum), ± medium chromosomes (P. crassipes, P. fulgidum, P. hirtum, P. hystrix, P. oreophilum, P. pulchellum, P. sericifolium, P. stipulaceum, and P. torulosum), II large chromosomes (p. exhibens, P. mollicomum, P. worcesterae)

266

F. ALBEP.S & al.:

Table 2. Hybridization attempts between species of sect. Ligularia and other Pelargonium species. * - N o seed set, 4- seed inviable, + F 1 hybrid parent

Accession number

2n

d' parent

Sect. Ligularia

P. ionidiflorum

2181

16 x p. ovaIe subsp, ovale 2237

articulatum ionidiflorum stipulaceum tenuicaule trifidum trifidum trifidum

2237

20 x p. exstipuIatum

U M 297 1874 1600 3061 742 742 1611

1273 1243 1243 1243 754 754 754 754 1883 1883

1600

16

18 16 22 36 18 18 18

x p. frutetorum x P. frutetorum x P. frutetorum

754 754 754 712 1243 754 1883

18 18 18 18 18 18 18

x x x x

p. inquinans p. acetosum P.fruterorum p. inquinans

1059 1656 2730 2089 1656 906 1874 742 U M 297 742

32 16 18 44 16 18 16 18 18 18

MS 150

44

1059 906 906

32 22 22

1105 MG 7 2260

22 22 22

F

m

m

18 18 18 18 18 18 18 18 18 18

x x x x x x x x x x

p. abrotanifolium p. p. exstipulatum p. trifidum p. xerophyton p. exstipulatum P.fulgidum p. ionidiflorum p. trifidum p. articulatum p. trifidum

m

F

F

22 x p. crassicaule Sect. Ligularia

2902 2902 779

Sect. Ligularia

P. exhibens P. fulgidum P. fulgidum

1656

Sect. Cortusina s. str.

Sect. Eumorpha

P. multibracteatum P. multibracteatum P. transvaalense

±

Sect. LiguIaria

Sect. Ligularia

P. stipulaceum

20

Sect. Cieonium

Sect. Ciconium

P. acetosum P. acetosum P. acetosum P. acetosum P. frutetorum P.frutetorum P. frutetorum P. frutetorum P. inquinans P. inquinans

*

Sect. Ligularia

Sect. Ligularia

P. P. P. P. P. P. P.

2n

Sect. CampyIia

Sect. Campylia

P. ovale subsp, ovale

Accession number

18 x p. abrotanifolium 18 x P. fulgidum 18 x P. fulgidum

F

m

m

Sect. Glaucophyllum 1889 C P G 79/32 K 1347

22 x p. grandiflorum 22 x p. grandiflorum 22 x p. lanceolatum

± +

Pelargonium sect. Ligularia

267

Table 2 (continued) parent

Accession number

2n

Sect. GIaucophyllum

P. P. P. P. P. P. P.

grandiflorum grandiflorum grandiflorum grand!florum laevigatum lanceolatum lanceolatum

1105 1105 1105 1105 3566A 2260 2260

x P. fulgidum x p. tenuicaule x p. trifidum x p. xerophyton x P. fulgidum x p. stipulaceum 22 x p. xerophyton

22 22 22 22 22 22

3061

36 x p. luteolum

3307

?

1656 1611 742

candicans candicans candicans candicans candicans caucalifolium caucalifolium caucalifolium myrrhifolium myrrhifolium

x p. xerophyton

16 x p. trifidum 18 x p. abrotanifolium 18 x p. exstipulatum

22 36 18 44 22 22 22

:k ± :t:

3105

?

2089

44

2730 1059 1656

18 32 16

782 1904

22 44

1059 906 2181 3061 2089 906 2181 A L & U M 83 906 2089

32 22 16 36 44 22 16 44 22 44

± ± ± ±

A L & U M 34

22

±

1277

22

Sect. Myrrhidium 1889 A L & U M 83

22 x p. candicans 22 x p. caucalifolium

Sect. Myrrhidium

P. P. P. P. P. P. P. P. P. P.

K 1347 3061 1611 2089 K 1347 2813 A L & U M 83

Sect. Ligularia

Sect. Ligularia

P. exhibens P. xerophyton

*

Sect. Ligularia

Sect. Ligularia

P. exstipulatum P. trifidum P. trifidum

2n

Sect. Hoarea

Sect. Hoarea

P. punctatum

Accession number

Sect. Ligularia

Sect. Ligularia

P. tenuicaule

c~ parent

±

Sect. Ligularia 782 782 782 782 782 1904 1904 1904 479 479

Sect. Ligularia

22 22 22 22 22 44 44 44 22 22

x p. abrotanifolium x P. fulgidum x p. ionidiflorum x p. tenuicaule x p. xerophyton x P.fulgidum x p. ionidiflorum x p. xerophyton x P. fulgidum x p. xerophyton Sect. Otidia

P. exhibens

1889

22 x p. carnosum

P. sericifolium

1680

22 x p. laxum

"rotundipetalum"

268

F. ALBERS & al.:

T a b l e 2 (continued) parent

Accession number

2n

3 parent

Sect. Otida

P. carnosum "rotundipetalum" P. dasyphyllum P. dasyphyllum P. laxum

exhibens exhibens stipulaceum xerophyton xerophyton xerophyton

A L & U M 34 2852 2852 1277

22 22 22 22

x P. abrotanifoIium x P.fulgidum x P. xerophyton x p. xerophyton

englerianum hermanniifolium sublignosum sublignosum sublignosum

1889 1600 A L & U M 83 A L & U M 83 A L & U M 83

22 22 22 44 44 44

x x x x x x

2430 728 1021 1021 1021

22 22 22 22 22

x x x x x

abrotanifolium abrotanifolium abrotanifolium abrotanifolium exstipulatum ionidiflorum ionidiflorum

1889 K 1347 1874

dichondrifoIium dichondrifolium dichondrifolium sidoides

p. p. p. p. p. p.

denticulatum hermanniifolium denticulatum denticulatum hispidum quercifoIium

p. p. p. p. p.

fulgidum fulgidum exhibens tenuicaule xerophyton

22 x p. gibbosum 22 x p. gibbosum 16 x p. gibbosum

+ :L +

2700 2700 2700 1006 1680

44 44 44 44 44 44

:t: + i :t:

K 1347 K 1347 1889 3061 A L & U M 83

22 22 22 32 22

+ :t: -

721 721 721

22 22 22

± -

1853 H i 950/78 1877 U M 636 1853 2804 2804

16 32 32 32 16 16 16

+ + + + -

1059 1656 742 1656

32 16 18 16

44-

Sect. Reniformia 1059 1059 1059 1059 1656 1874 1874

32 32 32 32 16 16 16

x x x x x x x

Sect. Reniformia

P. P. P. P.

32 22 44 44

Sect. Polyactium

Sect. Ligularia

P. P. P. P. P. P. P.

1059 K 1347 2089 2089

Sect. Ligularia

Sect. Ligularia

P. exhibens P.fulgidum P. ionidiflorum

*

Sect. Pelargonium

Sect. Pelargonium

P. P. P. P. P.

2n

Sect. Ligularia

Sect. Ligularia

P. P. P. P. P. P.

Accession number

p. p. p. p. p. p. p.

dichondrifolium sidoides sidoides sidoides dichondrifolium odoratissimum odoratissimum

Sect. Ligularia 1853 1853 1853 1877

16 16 16 32

x x x x

p. p. p. p.

abrotanifolium exstipulatum trifidum exstipulatum

Pelargonium sect. Ligularia

269

(1820- 1830). One of the most popular species used in crosses at this time was P. fulgidum, because of its bright scarlet petals, and the relative ease with which it could be hybridized; many of the hybrids described by SWEET were of complex parentage, but the F 1 hybrids involving P. fulgidum that he described are listed in Table 3, together with successful crosses of species of sect. Ligularia by later workers. Discussion

The 33 species of sect. Ligularia studied here show a wide variation in basic chromosome number and in chromosome size, and this contrasts markedly with, for example, sect. Pelargonium, where all the species have small chromosomes with x -- 11. Such a degree of karyological variation in Ligularia makes one suspect that the basis for the classification of this section may be artificial, and that the species do not represent a monophyletic group. All the basic chromosome numbers found in sect. Ligularia can be found elsewhere within the genus, and it is possible that some species at present classified within sect. Ligularia have closer affinities with species from outside this section that share the same basic chromosome number, than with other species of sect. Ligularia that have a different chromosome number. By grouping species according to their basic chromosome number, and comparing their karyology, morphology, distribution and the results from hybridization studies, we can try to identify closely related groups of species. Basic chromosome number x = 8. The basic chromosome number x = 8 is relatively uncommon within Pelargonium, and has been found elsewhere only in five species of sect. Reniformia (DREYER & al., unpubl.) - P. album J. J. A.VAN DEe. WALT, P. dichondrifolium (as P. cradockense in Yu & HORN 1988), P. odoratissimum (TAKAGI 1928), P. reniforme CUe.T. and P. sidoides (Yu & HORN 1988), in species of sect. Peristera- P. nahum L'HgRIT. and P. dispar N. E. BROWN, (ALBERS, GIBBY, unpubl. data) and some populations of P. alchemilloides (sect. Eumorpha, GIBBV & WESTFOLD 1986). From morphological comparison, the species of sect. Ligularia with x = 8 appear to be most closely related to the species of sect. Reniformia. P. abrotanifolium and P. exstipulatum are both aromatic shrubs with very similar floral morphology; P. album, P. dichondrifolium, and P. odoratissimum also have aromatic foliage and similar floral structure. P. ionidiflorum is closest in floral morphology to P. reniforme and P. sidoides, rather than to other species of sect. Ligularia. These morphological similarities are supported by the similarity in chromosome size, and in the successful synthesis of F 1 hybrids; in addition to the three hybrids reported here - P. exstipulatum x p. dichondrifolium, P. ionidiflorum x p. odoratissimum, P. abrotanifolium x p. sidoides - Yu (1985) found 92% pollen fertility in the synthesized hybrid P. abrotanifolium x p. sidoides. This is similar to the fertility that is usually found for a Pelargonium species. A more natural classification would be achieved by placing the three species of sect. Ligularia with x = 8 in the new section Reniformia (DRE'ZEe` & al., unpubl.) (see Table 4). Basic chromosome number x = 9. P. barklyi, which was originally placed in sect. Polyactium by ScoTT ELLIOTa" (1891) on account of its underground tuber, and then by KNua-n (1912) in sect. Hoarea, is included in sect. Ligularia by VAN D~P, WALT & Voe`s'rze. (1988) because the flowers and leaves resemble P. articulatum, and the two species have the same basic chromosome number. BLACKMAN(1990 b)

270

F. ALBERS & al.:

Table 3. Successful Pelargonium breeding attempts of other authors. * 4- Inviable seed, or short-lived seedlings; 4- F 1 hybrid, + ? seed set but not sown parent

2n

~ parent

Sect. Ligularia

P. fulgidum P. hirtum P. hystrix P. ionidiflorum P. pulchellum

x x x 16 x x

32 x p. tricolor

18 x P. zonaIe

18 x p. aridum 18 x p. aridum

x p. grandiflorum

Sect. Hoarea

P. pinnatum? P. pinnatum Sect. Ligularia

P. fulgidum Sect. Pelargonium

P. cucullatum

4- Y u (1985)

18

4- Y u (1985)

18 18

4- Yu (1985) 4- Y u (1985)

+ SWEET 2:289

Sect. Ligularia

x P. fulgidum

Sect. Ligularia

P. fuIgidum P. fulgidum P. fulgidum P. fulgidum P. fulgidum P. fulgidum

36

Sect. Glaucophyllum

Sect. Glaucophyllum

P. grandiflorum

SWEET 3:297 SWEET 3:233 DE MARIE (1990 a) Y u (1985) SWEET 4:313

Sect. Ligularia

Sect. Ligularia

P. fulgidum

18

+ + + 4+

Sect. Ciconium

Sect. Ciconium

P. inquinans P. zonale

p. pulchelIum ? p. fulgidum p. sericifolium P. aridum p. fulgidum Sect. Campylia

Sect. Ligularia

P. aridum

* Reference

Sect. Ligularia

Sect. Ligularia

P. abrotanifolium

2n

+ SWEET 2:127

Sect. Hoarea

× × × × × ×

P. auritum vat. auritum P. pinnatum P. pinnatum P. rapaceum P. rapaceum? P. rapaceum

+ + + + + +

SWEET 2:170 SWEET 3:220 SWEET 4:301 SWEET 3:237 SWEET 3:256 SWEET 4:305

Sect. Ligularia

x P. fulgidum x P. fulgidum

+ SWEET 2:121 + SWEET 3:202

Sect. Pelargonium

x p. radens

+ SWEET 2:153

Sect. Ligularia

x P. fulgidum

+ SWEET 1:81

Pelargonium sect. Ligularia

27l

Table 3 (continued) parent

2n

c? parent

Sect. Polyactium P. bowkeri P. lobatum P. lobatum

abrotanifolium abrotanifolium ionidiflorum ionidiflorum

Sect. Reniformia P. reniforme P. sidoides

*

Reference

22

+ + +

Yu (1985) SWEET1:45 BLACKMAN(1990 a)

32 32 16 32

+? + 4+?

Yu Yu Yu Yu

32 32

+ ? Yu (1985) +? Yu (1985)

Sect. Ligularia 22 x p. stipulaceum x p. fulgidum x p. fulgidum

Sect. Ligularia P. P. P. P.

2n

Sect. Reniformia 32 32 16 16

x x x x

p. p. p. p.

reniforme sidoides dichondrifolium reniforme

(1985) (1985) (1985) (1985)

Sect. Ligularia 32 x p. abrotanifolium 32 x p. abrotanifolium

has produced fertile hybrids between P. articulatum and a cultivar of a zonal Pelargonium (x = 9, sect. Ciconium). A close relationship between P. aridum and sect. Ciconium may be inferred from the crosses made by Y u (1985) with P. zonale and P. inquinans (Table 3), although the F 1 hybrids were short lived; this is also supported by isozyme studies (Yu 1985). Following breeding work in which the technique of embryo rescue was employed, DE MARIE (1990 b) synthesized hybrids of both P. aridum and P. barklyi with species of sect. Ciconium (see Table 3), and he suggested that P. aridum, P. articulatum, and P. barklyi should be transferred to sect. Ciconium as revised by VAN DER WALT & VORSTER (1988). P. dolomiticum, P. griseum, and P. tragacanthoides have similar floral morphology, the inrolled claws of the upper two petals being unique to these three species of Pelargonium (VANDER WALT & VORSTER 1988); all are atypical of sect. Ligularia in that they are distributed for most of their ranges in the summer rainfall area of South Africa. The karyological data supports the evidence for a close relationship between these species. Of the other four species of sect. Ligularia with x = 9, only P. divisifolium and P. plurisectum appear to be closely related on morphological evidence (VORSTER 1987) to any of the six species with x = 9 mentioned above, or to each other. The morphological diversity may be related to geographical distribution or climate. P. articulatum, P. barklyi, and P. tenuicaule are found in the more arid regions of the winter rainfall area. P. divisifolium and P. plurisectum are components of the SW. Cape fynbos, whereas P. aridum, P. griseum, P. tragacanthoides, and P. dolomiticum all receive summer rainfall over most or all of their distributions. P. trifidum extends from the SW. Cape to the eastern karoo, and receives summer as well as winter rainfall. It has previously been suggested that two species of sect. Jenkinsonia with x = 9, P. praemorsum (ANDR.) DIETR. and P. antidysentericum (ECKL. & ZEUR.) COSTEL., are related to P. trifidum (GIBBY & al. 1990), but SCnELTEMA & VAN DER

272

F. ALBERS & al.:

Table 4. Proposals for a subdivision of sect. Ligularia based on karyology and hybridization experiments

x=8

x=ll

P. ionidiflorum P. exstipulatum P. abrotanifolium

P. desertorum P. xerophyton

sect. Cortusina

P. alpinum

close to sect. Pelargonium

sect. Reniformia (DREYER & al., unpubl.)

x=9

P. aridum P. barklyi P. articulatum P. dolomiticum P. griseum P. tragacanthoides P. divisifolium P. plurisectum P. trifidum P. tenuicaule

close to sectt. Ciconium & Eumorpha

new section, probably including P. praemorsum & P. antidysentericum

P. crassipes P. hirtum P. hystrix P. oreophilum P. pulcheIlum P. stipulaeeum P. torulosum

remaining sect. Ligularia s. str.

P. sericifolium P. fulgidum P. exhibens P. mollicomum P. worcesterae

uncertain position

x=10 P. P. P. P.

grandicalcaratum karooieum otaviense spinosum

P. setuIosum

new section

sect. Campylia VAN DER WALT c~¢ ROUX

(1992)

WALT (1990) still retain them in sect. Jenkinsonia, which in our opinion is an artificial section. The inclusion of these two species from sect. Jenkinsonia together with all the species of sect. Ligularia with x--9, excepting P. aridum, P. barklyi, and P. articulatum, may prove to be an acceptable classification (see Table 4). Basie ehromosome number x = 10. The basic c h r o m o s o m e n u m b e r x = 10 is not c o m m o n in Pelargonium, but outside sect. Ligularia is reported from a few species of sect. Hoarea (P. tysonii SzYsz., P. rapaceum JACQ., NORDENSTAM 1969, DAKER 1969; P. nervifolium JACQ., P. carneum JACQ., ALBERS, GIBBY, unpubl, data), and all of sect. Campylia (by B. PRINSLOO in VAN DER WALT • VAN ZYL 1988; VAN DER WALT & al. 1990b, c; VAN DER WALT (~ ROUX 1992). P. otaviense and P. spinosum share a n u m b e r of c h a r a c t e r s - glaucous leaves, long, persistent petioles, identical karyotypes and similar geographical distribution, but differ in their leaf and floral structure, and pollen m o r p h o l o g y (VAN DER WALT (~¢ al. 1990a). P.

Pelargonium sect. Ligularia

273

grandicalcaratum with the same basic chromosome number, x = 10, has the same peculiar floral morphology as P. otaviense, with semi-closed flowers and a thick h y p a n t h i u m - features that must surely be associated with an unusual pollination mechanism. P. karooicum, also with x = 10, is not typical for sect. Ligularia in that it has only 5, rather than 7, fertile stamens, although reduced stamen number is found also in three species with x = 11, P. exhibens (5), P. hystrix (4), and P. torulosum (4). The four species of sect. Ligularia with x = 10 mentioned above have no obvious morphological affinities with any Pelargonium species with the same basic chromosome number. However, P. setulosum (x = 10) which has smaller chromosomes than the other four species (compare Figs. 11, 12 with Figs. 7 - 10) shows clear morphological and karyological affinities with species of sect. Campylia, to which section it is now transferred (VANDEP. WALT & R o u x 1992). Basic chromosome number x = 11. The basic chromosome number x = 11 is by far the most commonly recorded number within the genus Pelargonium, having now been found in 13 of the 17 sections; ALBERS & VAN DEP, WALT (1984) have suggested that this is the primitive basic number for the genus. From morphological evidence, the species of sect. Ligularia with x = 11 do not form a single closely related group, and this is also clear from the cytological data, as the karyotypes differ in size. The correlation between karyotype and geographical distribution is marked (Fig. 2). The species from the SW. Cape and Namaqualand have similar medium sized chromosomes with the exception of P. alpinum, P. xerophyton, and P. desertorum that have very small chromosomes. The species from the eastern Karoo, P. mollicomum, P. worcesterae, and P. exhibens, have comparatively large chromosomes. This karyological and geographic coincidence is also supported by morphological characters, allowing a classification of the 15 species with x = 11 into four groups (see Table 4). P. xerophyton and P. desertorum are close to each other in many respects, and it has already been proposed that they should be included in sect. Cortusina s. str. (DREYER & al., unpubl.). In vegetative morphology P. desertorum resembles P. otaviense, though differs in its recurved petals, and chromosome number and size. The taxonomic position of the third species with small chromosomes, P. alpinum, is still doubtful, although to some extent it resembles P. sericifolium in morphology (VANDER WALT & VORSTER 1988). The distinct life form may reflect the unique habitat for a Pelargonium, high in the mountains near Tulbagh and Ceres where there is winter snow. HARVEY (1860) placed this species in sect. Cortusina DC. From the karyotypic evidence, P. alpinum (Fig. 13) should be classified in a section with small chromosomes and x = 11, for example sect. Pelargonium. Most of the species with medium sized chromosomes have been grouped together on morphological characters by several a u t h o r s - P. oreophilum with P. hystrix and P. hirtum (VAN DEe, WALT 1977, VAN DER WALT & VORSTER 1981), P. stipulaceum with P. hystrix and P. torulosum (MARAIS 1990). In addition, a relationship has been proposed between P. stipulaceum and P. hirtum from comparison of isoenzyme patterns (Yv 1985), and between P. stipulaceum and P. pulchellum from morphology (VANDEe, WALT & VORSTER 1981). These latter authors also suggest an affinity of P. pulchellum and P. stipulaceum with species of sect. Cortusina s. str. All these species are confined to the winter rainfall area; P. sericifolium, P. crassipies, and P. fulgidum from this same geographic area may be

274

F. ALBERS& al.:

more distinctly related to this group. P. sericifolium has been crossed successfully with P. hystrix, using the technique of embryo rescue (DE MARIE 1990 a), and the resulting hybrids are partially fertile. P. fulgidum, that was transferred to sect. Ligularia by VAN DEP, WALT & VORSTER (1988), has a unique floral structure, relating to the fact that it is pollinated by birds (VOGEL 1956). This species was classified in sect. Polyactiurn by KNua-I~ (1912), despite the fact that it lacks tubers and has fleshy stems, unlike the majority of species in this section. P. fulgidum appears to be remarkable in its ability to hybridize with a wide variety of species, including P. hirturn and P. puIchellum (sect. Ligularia), P. cucullatum (L.) L'HgRIT. (sect. Pelargonium), P. grandiflorum (sect. Glaucophyllum), P. auritum (L.) WILLD. and P. rapaceum (sect. Hoarea), and P. lobatum (BuRM. f.) L'HI~RIT. (sect. Polyactium) (see Tables 2, 3). However, despite their wide variation in morphology, most of the species with which P. fulgidurn crosses readily have the same chromosome number, 2 n--22, the sole exception being the crosses with P. rapaceum that has x = 10. Presumably under natural conditions P. fulgidum will be unlikely to hybridize with other species, as no other PeIargoniurn species shares the same pollinator as P. fulgidum. Despite the highly derived floral morphology in some species of sect. Ligularia with x = 11 from the SW. and western part of Cape Province, particularly in the case of P. fulgidurn, these species form a closely related group, and we suggest that this complex should be retained as sect. Ligularia s. str. (Table 4). Several of these species have affinities with those of sect. Cortusina s str. (DREYER• al., unpubl.), in morphology and karyology, but no successful crosses between them have yet been synthesized. The three eastern Cape species, P. mollicomum, P. worcesterae, and P. exhibens, form a separate small complex. The first two have been linked to P. odoratissirnurn and P. dichondrifolium (sect. Reniforrnia) on account of their habit, leaf shape and scented foliage (VAN I~ER WALT 1977, VAN I~ER WALT & VORSTER 1988), but the floral structures and karyology differentiate them. The taxonomic position of these species in the genus is uncertain. This study demonstrates that sect. Ligularia is an artificial assemblage of species. With the aid of karyological features, the section can be divided into smaller natural groupings that are supported by morphological characters and crossing experiments. We make no formal suggestions for excluding or tranferring species, but rather provide advice and information (Table 4). Only by using data from a broad multidisciplinary approach can a new classification for these 33 species be undertaken reliably. The authors would like to thank Prof. J. J. A. VANDER WALT and Dr P. VORSTERfor making their collections available for study and for valuable comments and discussions. The first author is grateful to the University of Stellenbosch, Republic of South Africa, and the Deutsche Forschungsgemeinschaft for financial support. The second author is grateful to the staff of Chelsea Physic Garden, London, who have cared for living collections, and to the Photographic Studio at the Natural History Museum, especially to PETERYO~K, for photographs. Referenees

ALBERS, F., VANDER WALT, J. J. A., 1984: Untersuchungen zur Karyologie und Mikrosporogenese von Pelargonium sect. PeIargonium (Geraniaceae). - P1. Syst. Evol. 147: 177- 188.

Pelargonium sect. Ligularia

275

BLACKMAN,C., 1990 a: Pelargonium lobatum × P.fulgidum. - Geraniaceae G r o u p News, Autumn: 5. - 1990b: Pelargonium × articulatum. - Geraniaceae G r o u p News, Autumn: 12. DAKER, M. G., 1969: C h r o m o s o m e number of Pelargonium species and cultivars, - J. Roy. Hort. Soc. 94: 3 4 6 - 3 5 3 . DE MARIE, E., 1990 a: " K a r o o Pride" a new hybrid of Pelargonium sericifolium × Pelargonium hystrix. - Hystrix 1: 3 7 - 3 9 . - 1990 b: A case for the transfer of three Pelargonium species from section Ligularia to section Ciconium. - Hystrix 2: 5 - 8 . GIBBY, M., 1990: Cytological and morphological variation within Pelargonium alchemilloides s.l. (Geraniaceae). - Mitt. Inst. Allg. Bot. H a m b . 23 b: 7 0 7 - 7 2 2 - WESTFOLD, J., 1986: A cytological study of Pelargonium sect. Eumorpha (Geraniaceae). - P1. Syst. Evol. 153: 2 0 5 - 2 2 2 . ALBERS, F., PRINSLOO, B., 1990: Karyological studies in Pelargonium sectt. Ciconium, Dibrachya and Jenkinsonia (Geraniaceae). - P1. Syst. Evol. 170:151 - 159. HARVEY, W. H., 1860: Pelargonium. - In HARVEY, W. H., SONDER, O., (Eds.): Flora Capensis 1, pp. 2 5 9 - 308. Dublin: Hodges & Smith. KNUTH, R., 1912: Geraniaceae. - In ENGLER, A., (Ed.): Das Pflanzenreich 4, 129. Leipzig: Engelmann. MARAIS, E. M., 1990: Pelargonium torulosum (Geraniaceae): a new species from the southwestern Cape Province, southern Africa. - S. African J. Bot. 56: 5 6 5 - 5 7 0 . NORDENSTAM, B., 1969: C h r o m o s o m e studies on South African vascular plants. - Bot. Not. 1 2 2 : 3 9 8 - 4 0 8 . SCHELTEMA, A. G., VAN DER WALT, J. J. A., 1990: Taxonomic revision of Pelargonium sect. Jenkinsonia (Geraniaceae) in southern Africa. - S. African J. Bot. 56: 2 8 5 - 302. SCOTT ELLiOt, G. F,, 1891: Novitates capensis. - J. Bot. (London) 29: 6 8 - 6 9 . SWEET, R., 1820-1822: Geraniaceae 1. - London: Ridgway. 1822-1824: Geraniaceae 2. - London: Ridgway. - 1824-1826: Geraniaceae 3. - London: Ridgway. 1 8 2 6 - 1828: Geraniaceae 4. - London: Ridgway. 1828-1830: Geraniaceae 5. - London: Ridgway. TAKAGI~ F., 1928: On the chromosome numbers of Pelargonium. - Sci. Rep. T 6 h o k u Univ., Ser. 4, Biol., 3: 6 6 5 - 6 7 1 . VAN DER WALT, J. J. A., 1977: Pelargoniums of Southern Africa. - Cape Town: Purnell. - Rou×, 1992: Is Pelargonium sect. Campylia monophyletic? - S. African J. Bot. (in press). - VAN ZYL, L., 1988: A taxonomic revision of Pelargonium section Campylia (Geraniaceae). S. African J. Bot. 56: 1 4 5 - 171. VORSTER, P. J., 1981: Pelargoniums of Southern Africa 2. - Cape Town: Juta. 1983: Phytogeography of Pelargonium. - Bothalia 14: 5 1 7 - 5 2 3 . 1988: Pelargoniums of Southern Africa 3. - Ann. Kirstenbosch Bot. Gardens 16. ALBERS, F., GIBBY, M., 1990 a: Delimitation of the section Glaucophyllum of Pelargonium (Geraniaceae). - P1. Syst. Evol. 171: 1 5 - 2 6 . MCDONALD, D. J., VAN WYK, N., 1990 b: A new species of Pelargonium with notes on its ecology and pollination biology. - S. African J. Bot. 56: 4 6 7 - 4 7 0 . - VENTER, H. J. T., VERHOEVEN, R., DREYER, L. L., 1990c: The transfer of Erodium inearnatum to the genus Pelargonium (Geraniaeeae). - S. African Tydskr. Plantk. 56: 560 - 564. VOGEL, S., 1954: Blfitenbiologische Typen als Elemente der Sippengliederung dargestellt anhand der Flora Sfidafrikas. - Botan. Studien 1: 1 - 338. VORSTER, P. J., 1986: Pelargonium exhibens (Geraniaceae): a new species fi'om the eastern Cape Province. - S. African Tydskr. Plantk. 5 2 : 4 8 1 - 4 8 4 . -

-

-

-

-

-

-

-

276

F. ALBERS~; al.: Pelargonium sect. Ligularia

1987: Pelargonium divisifolium (Geraniaceae): a new species from the south-western Cape Province. - S. African J. Bot. 53:71-74. Yu, S.-N., 1985: Untersuchungen zur interspezifischen Kompatibilit/it und Biosystematik bei der Gattung Pelargonium. - Diss. Fak. Landw. u. Gartenb. Techn. Univ. MiinchenWeihenstephan. - HORN, W. A. H., 1988: Additional chromosome numbers in Pelargonium (Geraniaceae). - P1. Syst. Evol. 159: 165-171. -

Addresses of authors: Prof. Dr F. ALBERSand Miss M. AUSTMANN,Institut fiir Botanik, Westf/ilische Wilhelms-Universitfit Mtinster, Schlossgarten 3, D-W-4400 Mfinster, Federal Republic of Germany. - Dr M. GIBBY*, Department of Botany, The Natural History Museum, Cromwell Road, London SW7 5BD, U.K. Accepted September 6, 1991 by F. EHRENDORFER

* To whom correspondence should be addressed.

Verleger: Springer-Verlag K G , Sachsenplatz 4-6, A-1201 Wien. - Herausgeber: Prof. Dr. Friedrich Ehrendorfer, Institut fiir Botanik und Botanischer G a r t e n der Universitfit Wien, R e n n w e g 14, A-1030 Wien. - Redaktion: R e n n w e g 14, A-1030 Wien. - Hersteller: A d o l f Holzhausens Nfg., Kandlgasse 19-21, A- 1070 Wien. - Verlagsort: Wien. - Herstellungsort: Wien. - Printed in Austria.