A Taxonomic Revision of the Type Section of Pelargonium L'hérit
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Bothalia 15, 3 & 4: 345-385 (3985) A taxonomic revision of the type section of Pelargonium L’Hérit. (Geraniaceae) J. J. A. VAN DER WALT* Keywords: Pelargonium (Gcraniaceae), taxonomic revision, type section ABSTRACT Twenty four species are recognized in this taxonomic treatment of the section Pelargonium which was last revised by Knuth in 1912, Most species occur in the south-western, southern and eastern Cape where they usually grow in rather moist, semi-shaded habitats, A key to the identification of the species has been compiled, and at least one illustration as well as a distribution map is presented for each species. The section is considered to be the most primitive section of the genus with a basic chromosome number of x = 11. INTRODUCTION last section Pelargium, included 22 species of the In the section Pelargonium more species than in current section Pelargonium. Knuth (1912) also fol any other section have contributed towards the ma lowed basically the same system as D e Candolle, and terial welfare of mankind. A very large number of divided the section Pelargonium (Pelargium) into se artificial hybrids, known as ‘Regal Pelargoniums’ or ven subsections. This subdivision was based on the ‘Martha Washingtons' in the USA, have been pro colour of the petals, leaf characters and the length of duced for ornamental purposes. Features of P. cu- the pedicel and hypanthium. cuilaium (L.) L’Hérit. can be seen in many of these In 1979 Van der Walt proposed P. cucullatum as hybrids, and this well-known species could be con the lectotype species of the genus Pelargonium. sidered as the most important ancestor. P. graveo- lens L’Hérit., P. radens H. E. M oore and other aro The section Pelargonium is distinguished by a matic species of the section are the ancestors of an combination of characters. Sweet (1812), De Can other group of artificial ornamental hybrids known dolle (1824), Ecklon & Zeyher (1835), Harvey as ‘Scented-leaved Pelargoniums’. Hybrids of P. (1860) and Knuth (1912) mentioned that the section graveolens, especially, are grown on a commercial is characterized by a shrubby habit, five petals of scale for the production of geranium oil which is which the posterior two are larger than the anterior used as a substitute for attar of roses in the perfume three, and the presence of seven fertile stamens. trade. Some of these authors mentioned additional diag nostic features such as the shape of the leaves and When L'Hêritier (1789) described the genus Pel the free stipules. argonium, he did not subdivide it. Sweet (1822) was the first to make a subdivision: he elevated L’Héri- The geographical distribution of the section was tier’s genus to tribal level and his tribe Pelargonieae discussed by Van der Walt & V orster (1983). T he 24 included genera such as Campylia Sweet. Jenkinso- species occur in the south-western, southern and nia Sweet and Pelargonium, which are currently con eastern Cape with a few species extending north sidered as sections of the genus Pelargonium. His eastwards as far as the eastern highlands of Zim genus Pelargonium included species of the currently babwe. The two highest concentrations of species, in recognized section Pelargonium as well as members the south-western and southern Cape, fall entirely of other sections such as Dibrachya Sweet. within the winter rainfall region. Many of them, De Candolle (1824) reduced Sweet’s tribe Pelar however, do not occur in close association with fyn- bos, but rather favour primitive, moist shaded habi gonieae to generic level as the genus Pelargonium, tats, often in association with forest precursors. The and subdivided the genus into 12 sections. One of species in the eastern Cape receive rain in winter as these sections, Pelargium (the current section Pelar well as summer, whereas those in the Transkei, Na gonium), was divided into four series. The present tal, Transvaal and Zimbabwe occur in a predomi species of the section Pelargonium were included in nantly summer rainfall region. his series Anisopeiala. Ecklon & Zeyher (1835) followed Sweet’s classifi The section Pelargonium is considered to be the cation system: they again raised the present genus most primitive section of the genus on account of its Pelargonium to tribal level as the tribe Pelargonieae, rather woody, much-branched, shrubby habit, sim which was divided into 15 genera. Their genus Pelar ple leaves, and five-petalled flowers with seven fer gonium included species of the current section Pelar tile stamens. Albers & Van der Walt’s (1984) chro gonium. mosome study of the section supported this view. The basic chromosome number of the section is x = Harvey (1860) followed De Candolle’s system and 11, which is m ost probably also the basic num ber for divided the genus Pelargonium into 15 sections. His the genus. Furthermore, the chromosomes are rela tively small in comparison with those of other sec * Botany Department, University of Stellenbosch, tions of the genus. Twelve species are diploid Stellenbosch 7600. (2n=22) and twelve polyploid (2n=44,66, 88). The 346 Bothalia 15, 3 & 4 (1985) two spccies occurring in the Transvaal, P. glutino- or serrate, 5-250 x 3-270 mm; petioles 0-250 mm sum (Jacq.) L’Hérit, and P. graveolens, are both long; stipules free, usually cordiform or triangular polyploids, which might indicate that the section had and often apiculate or cuspidate, 2-20 x 1-15 mm. a southern origin. Inflorescences: flowering branches in some species Many spccies show continuous morphological va profusely branched, with smaller and normal foliar riation, an indication that they are probably still in leaves or smaller foliar leaves only; peduncles un an active state of speciation. Natural hybrids be branched, in some species distinctly articulated at tween representatives of the section Pelargonium, as distal and proximal ends in infructescences, 5-150 well as hybrids between representatives of the sec mm long, indumentum variable as on stems; invo- tion Pelargonium and the sections Eumorpha (Eckl, lucral bracts mostly ovate or lanceolate, apiculate & Zeyh.) Harv. and Glaucophyllum Harv., have to caudate, 3-10 x 1-7 mm, indumentum variable as been collected. A list of these hybrids with their pu on stems; pseudo-umbels with 1-20 flowers each. tative parent species, is presented at the end of the Pedicels 0,5-20 mm long, shorter or longer or as long paper. as hypanthiums. Hypanthiums 1-14 mm long, base variably thickened, indumentum on pedicels and hy This paper represents an alpha taxonomic treat panthiums variable as on stems. Sepals 5, usually ment of the section. The species are phylogenetically lanceolate, often apiculate, green and often with a arranged, but the relationships of the species will be reddish-brown tint, in some species with white mar discussed in detail in a following paper. In order to gins, posterior one wider than other four, 7-20 X do so, use will be made of additional features, viz 2-6 mm. Petals 5, white, pink, pinkish-purple o r pur anatomy, pollen morphology and cytotaxonomy. ple; posterior two usually spathuiate or obovate, apices often emarginate, with dark purple, wine-red Section Pelargonium: DC-, Prodr. 1: 658 (1824) or dark red feather-like markings, reflcxed at less (series IV, Anisopeiala DC. p.p.); Harv. in FI. Cap. than 90°, 90° or more than 90°, 6-35 x 3-17 mm; ante 1: 301 (1860); Knuth in Pflanzenr. 4, 129: 320, 455 rior three usually spathuiate or oblanceoiate, with or (1912) — all as Pelargium. Lectotypc spccies: Pelar without narrow claws, reflexed at less than 90°, 4-28 gonium cucullatum (L.)L’Hérit. (see Van der Walt x 2-12 mm. Fertile stamens 7 (4 long, 1 medium, 2 in Jt S. Afr. Bot. 45,3: 379-380 (1979) and Van der short), often pinkish but becoming progressively Walt & Vorster in Taxon 30: 307 (1981). paler towards hyaline staminal column, pollen orange; staminodes 3. Ovary 5-lobed, usually ovoid, densely pilose with apicaily directed hairs, white to Genus Pelargonium: Sweet, Geran. 1: viii, 41 green; style 5-12 mm long, base variably hairy; (1821) p.p.; Eckl. & Zeyh., Enum. 1: 78 (1835). stigma with 5 recurved branches, purple to reddish; Erect to decumbent, branched to much-branched, mcricarps 5, bases 3-6 mm long, tails 12-30 mm non-aromatic to aromatic, non-viscid or viscid long, plumose. 2n=22, 44, 66 or 88. shrubs or subshrubs, up to 2,5 m high and 1,6 m in Diagnostic features diam eter. Stems herbaceous when young, becoming variously woody with age, sparsely to densely cov Erect to decumbent, non-aromatic to aromatic, ered with different types of non-glandular and glan non-viscid or viscid subshrubs or shrubs with rather dular hairs, young stems green but becoming greyish woody stems. Leaves simple, laminae entire to vari to brownish with age. Leaves simple, petioiate, ously palmately or pinnately incised. Inflorescences: stipulate, indumentum variable as on stems, dark flowering branches with smaller and normal foliar green, green o r greyish green: laminae entire to vari leaves or smaller foliar leaves only, pseudo-umbels ously palmately or pinnately incised, shape variable with 1-20 flowers each. Flowers white, pink, pink but often cordiform , base usually cordate seldom cu- ish-purple or purple; posterior petals with dark pur neate or truncate, apices of laminae/lobes/segments ple, wine-red or dark red feather-like markings; fer obtuse or acute margins finely to coarsely dentate tile stamens 7 (4 long, 1 medium, 2 short). KEY TO THE SPECIES OF THE SECTION PELARGONIUM 1 Laminae without incisions or very shallowly lobed: 2 Mature laminae less than 20 mm long: 3 Laminae glabrescent to hirtellous: 4 Laminae without incisions, circular to broadly elliptic to ovate and not viscid ...........