560 S.-Afr.Tydskr.Plantk., 1990,56(5): 560-564 The transfer of Erodium incarnatum to the genus PeJargonium (Geraniaceae)
J.J.A. van der Walt*, H.J.T. Venter1, R. Verhoeven 1 and L.L. Dreyer Department of Botany, University of Stellenbosch, Stellenbosch, 7600 Republic of South Africa and 1Department of Botany, University of the Orange Free State, Bloemfontein, 9300 Republic of South Africa
Accepted 3 J uJy 1990
Erodium incarnatum L'Herit. was placed in the genus Erodium on account of its actinomorphic flowers and five fertile stamens. A study of the flower revealed atypical characters such as the presence of a staminal column and absence of nectariferous glands on the receptacle. A natural hybrid between E incarnatum and Pelargonium patulum Jacq. was discovered. The transfer of E incarnatum to Pelargonium by Moench in 1802 is supported and the correct name of the plant is Pelargonium incarnatum(L'Herit.) Moench.
Erodium incarnatum L'Herit. is in die genus Erodium geplaas op grond van sy aktinomorfe blomme en vyf vrugbare meeldrade. 'n Studie van die blom het atipiese kenmerke soos die aanwesigheid van 'n meeldraadsuil en die afwesigheid van nektarkliere op die blombodem, aan die lig gebring. 'n Natuurlike hibried tussen E incar natum en Pelargonium patulum Jacq. is ontdek. Die oorplasing van E incarnatum na Pelargonium deur Moench in 1802 word ondersteun en die korrekte naam van die plant is Pelargonium incarnatum (L'Herit.) Moench.
Keywords: Erodium incarnatum, Geraniaceae, Pelargonium, taxonomy
*To whom correspondence should be addressed
Introduction Pollen morphology The genus Erodium L'Herit. is characterized by five free The pollen grains of E. incarnatum are more or less spherical stamens, five free staminodes and five nectary glands with a polar diameter of ca. 65 f..Lm (Figure 2A). They are alternating with the bases of the petals (Guittonneau 1972). tricolporate with relatively long colpi (Figure 2B). The The flowers of most species are actinomorphic. tectum can be described as reticulate-striate. The striate Several exotic species of Erodium occur as weeds in South appearance is due to some lirae being on a higher level, more Africa (Venter & Verhoeven 1990), E. incarnatum L'Herit. or less parallel to each other and more prominent than others. being the only indigenous one. This species was placed in the Verhoeven & Venter (1987) studied the pollen grains of genus Erodium on account of its actinomorphic flowers and seven Erodium species, including that of E. incarnatum. The five fertile stamens. A close inspection of the flower, reticulate-striate tectum of E. incarnatum is not typical of Erodium, but it resembles that of several Pelargonium however, revealed certain characters atypical of Erodium species. The tectum of E. incarnatum is for example almost placing its classification in doubt. identical to that of P. tricolor Curtis (van der WaIt & van Zyl In this study more characters of E. incarnatum were 1988). investigated to ascertain the classification of this interesting species. Somatic chromosome number Floral morphology The somatic chromosome number of E. incarnalum has been determined by Albers (pers. comm.) as 2n = 40. Two The flower of E. incarnatum appears actinomorphic although satellites are responsible for previous erroneous counts of 2n two petals are often slightly smaller than the other three. The = 42. androecium consists of five fertile stamens and five stamin A somatic chromosome number of 2n = 40 is commonly odes, and the bases of the filaments are fused to form a found in Erodium (Guittonneau 1972), but this number was staminal column. A staminal column is atypical of Erodium also recorded in Pelargonium. Van der WaIt & van Zyl (Guittonneau 1972). (1988) concluded that the basic chromosome number of The typical nectariferous glands on the receptacle of Pelargonium section Campylia is x = 10 and somatic Erodium are lacking in the flower of E. incarnatum. In some chromosome numbers of 2n = 20, 40 were reported. P. flowers, however, a shallow cavity is present opposite the ocellatum J.J.A. v.d. Walt, a newly described species in posterior sepal (Figure 1). These cavities occur in flowers section Campylia (van der WaIt el al. 1990b), also has a from different populations. No nectariferous glands or even somatic chromosome number of 2n = 20. The habit and nectariferous tissue were observed in the cavities. Similar leaves of E. incarnalum markedly resemble those of P. shallow cavities are present in the flowers of some species of ocellatum. Pelargonium section Campy/ia (Sweet) DC. (van der Walt & The chromosomes of E. incarnalum are relatively small van Zyl 1988). No information on the pollination biology of and comparable in size to those of section Pelargonium E. incarnatum is known, but it seems likely that it relies (Albers & van der WaIt 1984) and section Glaucophyllum entirely on the decoration of the corolla to attract pollinators. Harv. (van der Walt et al. 1990a). S.AfrJ.Bol, 1990,56(5) 561
Figure 1 Longitudinal section of the flower of Erodium incar natum illustrating the shallow cavity opposite the posterior sepal [van der Walt 1568 (STEU)]. P, petal; S, sepal.
Hybrid between E. incarnatum and Pelargonium Figure 2 Pollen grains of Erodium incarnatum [Boucher 2000 patulum (STE)]. A, polar view; B, aperture. Scale bar = 10 fLm. A natural hybrid between E. incarnatwn and P. patulum Jacq. was collected in Viljoens Pass near Grabouw [van der Walt Sweet: t.94 (1821); Steud.: 365 (1821), 579 (1841); D.C.: 648 1557a (STEU)] where the parent species grow together. The (1824); Harv.: 258 (1860); Kunth: 232 (1912). corolla of the hybrid has the typical colour and markings of E. Geranium incarnalum L.f.: 306 (1781). nom. illeg. (1781); Cav .: incarnatum, but the petals are grouped into two posterior and three anterior ones, giving the flower a zygomorphic appear 223 (1787); Thunb.: 112 (1794). 511 (1823); Andr. : C.ic. (1805). ance. The leaves of the hybrid, howeve., very strongly non L.: 1142 (1759). resemble those of P. patulum (Figure 3). P. patulwn has a Erodium pulchrum Salish.: 311 (1796). Type: as for Pelargonium somatic chromosome number of 2n = 44 and it belongs to the incarnatum. section Glaucophyllum Harv. The chromosome number of the hybrid has not yet been determined and it will most probably be sterile. Intergeneric hybrids are rare (Stace 1980) and the discov ery of a natural hybrid between E. incarnatum and P. patulum provided the last evidence needed to transfer E. incarnatwn to the genus Pelargonium. The new name for E. incarnatum will be P. incarnatum (L 'Herit.) Moench and it is placed in section Campylia.
Nomenclature Pelargonium incarnatum (L' Herit.) Moench, Supple mentum ad methodum plantas. In officina nova libraria academiae, Marburg: 295 (1802). Type: Cape Province, 'in Cap. bonae spei', Thunberg. s.n. (UPS, Thunberg herb. no. 15532, holo., photo seen). Figure 3 Flowering branch of the hybrid Erodium Incarna Erodium incarnatum L'Herit.: 415 (1789), t.5 (1792); Curtis: tum X Pelargonium pa/ulum [van der Wall 1557a (STEU)] t.261 (1794); Willd.: 637 (1800), 700 (1809); Pers.: 225 (1806); (X 0.6). 562 S.-Afr.Tydskr.Plantk., 1990,56(5)
A
c D' tI f, ~X4 .. ~ X4
Figure 4 Pelargonium incarnatum [Ward s.n. (STEU)]. A, branch with leaves and flowers X 1; B, petals X 2; C, androecium X 4; D, gynoecium X 4. S.AfrJ.Bot., 1990,56(5) 563
Geranium incarnatum L.f. (1781) is a later homonym of G. it has a rather small distribution area (Figure 5). The main incarnatum L. (1759) and therefore illegitimate. However, centre of distribution is in the Caledon district. It inhabits Article 72 (Note 1) of the Code (1988) permits the use of an mountainous country and it is most often present on southern epithet of an illegitimate name in 'a new position or sense', in and eastern slopes. It seems to occur mostly on sandy soils this case another genus. Hence Erodium incarnatum L'Herit. but it may be present on rocky or gravelly soils as well. P. is treated as a new name dating from 1789 and serves as the incarnatum is a component of short mountain fynbos where it legitimate basionym of the combination Pelargonium incar may be rare, occasional or common. natum (L'Herit.) Moench (1802). The type of P. incarnatum will be the type of Geranium incarnatum L.f. Specimens studied -3319 (Worcester): Bainskloof (-CA), Rogers 29282 (GRA); Description Worcester (-CB), Marlolh 84 (PRE), Slokoe 1122 (PRE), Decumbent, soboliferous subshrub, up to 0.2 m high. Stems Middlemosl 2312 (NBG); Franschhoek Pass (-CC), Rodin 3078 herbaceous and green to reddish when young, becoming (K), Galpin 12395 (K, PRE); VilJiersdorp (-CD), Oliver 5482 woody and brownish with age, glabrous to sparsely hirsute (STE), Gibby & Cromplon 52 (BM, STEU); lonaskop (-DC), van and with a few glandular hairs. Leaves alternate, crowded at der Wall 913,974 (STEU); Robertson (-DD), Barker 1143 (NBG): top of branches, green to reddish, sparsely hirsute with Onklaar (-DD), Slokoe 7054 (K). glandular hairs in between; lamina trilobate to trifoliolate, -3418 (Simonstown): Ciovelly (-AB) , Rogers 29265 (SAM); cordiform to broadly ovate, base obtuse to cordate, 12-20 Gordons Bay (-BB), Davis SAM-66681 (SAM), Tredgold 723 (-34) X 12-25(-36)mm; segments/pinnae often obcuneate (BOL); Helderberg Nature Reserve (-BB), van der Wall 1322 with the margins irregularly incised, terminal one often (STEU), Venier 8640a (BLFU); Sir Lowrys Pass (-BB), Schlechler pinnately incised, apices acute to obtuse and often reddish; 396 (PRE), 7277 (K), Drt}ge 966 (P, PRE), Salter 9033 (BOL) , petiole much longer than lamina, 25-125 mm long, often MacOwan 1414 (SAM, STE), Leighlon 820 (BOL), Complon partially persistent; stipules subulate, fused with petiole, 8-12 16540 (NBG), GUlhrie 2783 (NBG); Hottentotsholland Mountains mm long. Inflorescence: flowering branches with smaller (-BB), Ecklon & Zeyher 5911 (PRE), Zeyher 2040 (K, P, PRE, foliar leaves, bearing 4-5-flowered pseudo-umbels; peduncle SAM). 20-700 mm long, sparsely to densely hirsute and with -3419 (Caledon): Palmiet River (-AA), Ecklon & Zeyher 454 (P, glandular hairs in between. Pedicel 10-40 mm long, SAM), Bolus 411 1 (BOL, NBG); Elgin (-AA), Rogers 28937 (K); indumentum as on peduncle. Sepals 5, lanceolate, abaxially Grabouw (-AA) , Adamson s.n. (BOL), Kruger 1605 (STE); hirsute with glandular hairs in between, 4-6 x 2 mm, apices Houwhoek (-AA), Maguire 1235 (BOL, NBG), van der Wall 1568 acuminate, sometimes a shallow cavity at base of posterior (PRE, STEU) , Vorsler 2902 (STEU), Willems 78 (NBG); Caledon sepal. Petals 5, obovate, retuse, pale pink with white and (-AB), Wallers 228 (NBG), Barker 168 (BOL), 3346 (NBG), Bolus deep pink zones and a dark red base. Stamens 10, 5 fertile and 8446 (NH), 9893 (PRE, BOL, NH), PRE41205 (PRE), Marlolh 5 staminodes, filaments basally fused forming a staminal 4255 (K), 6107 (PRE), Zeyher 14530 (SAM), Bond 1682 (NBG), column ca. 2 mm long. Ovary ovate, 5-lobed, pilose; style Galpin 3834 (PRE), Complon 12399 (NBG); Highlands State 1-2 mm long; stigmas 5, 1-2 mm long. Mericarps: bases 3-4 Forest (-AC), Boucher 2000 (K, STE); Botrivier (-AC), Thomas mm long; tails 25-40 mm long. Figure 4. anno 1963 (NBG), Taylor 3791 (NBG), 4853 (STE), Burgers 330 P. incarnatum flowers from late October to January and (K, STE); Shaws Pass (-AD), Levyns 11239 (BOL), ESlerhuysen peaks during late November/early December. 19279 (Bol); Hartebees River (-BC), Elbrechl 22137 (PRE); P. incarnatum is endemic to the south-western Cape where Arieskraal (-BD), Leighlon 806 (BOL), Lewis 1170 (SAM).
Acknowledgements ". ". ". ". ,~ ". ". ". ,~ ". ". ,.. We are indebted to the following institutions and persons: the J:. 1v 1'\ ~ T . _;- , f ". ". ~f - f ~" V"itt f' Foundation for Research Development, Pretoria and the \ Research Fund of the University of Stellenbosch for financial , ~ ·1~rri8~! ti-:~B11 " support; Prof. F. Albers for the chromosome counts; and ~\\11\ ". ' lei 11] -,--' ". Ellaphie Ward-Hilhorst for executing the water colour 'I I) -' - j 1 v: ! r- H--H I \ I I'. painting that accompanies the paper. ,.. I ~ 111/ I \ !J--t-H-r- +.. \ r )r--t-t- j 11: -i---; --~- References 2&° r- Y 1 ' ,'. ir-1 j : : +.. I'" J 0' ... . J·rn lU-rf ALBERS, F. & VAN DER WALT, 1.I.A . 1984. Untersuchungen ,~ i'\; l
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