Gerbera Ambigua

Characteristics of the Gerbera Ambigua:

Gerbera Ambigua

Roots thong-like, 1-2.5(_) mm wide. Crown whitish silky-villose. Leaves highly variable in length, form and hair-covering, 5.2-38.5 cm long, 1.3-9.5 cm wide. Petiole terete or flattened and then often broadly grooved above, sometimes more or less winged by the :t decurrent lamina. (0-)1-20 cm long (excluding the winged part if present), 1-3(_) mm wide, up to 10 mm at the very base, whitish or sometimes brownish-reddish silkyvillose or tomentose-villose, becoming almost glabrous with age. Blade 3-29.5 cm long, lanceolate-oblanceolate, elliptic, oblong or rarely ovate or subrotund, obtuse or subacute towards the summit; base cuneate, decurrent or more rarely truncate or subcordate-cordate; margin entire or sinuate, always with rather remote, sometimes obscure teeth. Upper surface green, varying from almost glabrous through somewhat hairy-pubescent to densely velvety pilose with light hairs; lower surface persistently whitish or more rarely yellow-lemon to brownish-yellow tomentose with short, matted. appressed hairs, overlaid by longer. intermingled whitish or yellow-reddish-brownish ones, especially along the nerves; margin ciliate or curled hairy in the same colours. Nerves usually prominent, on the lower surface often raised, sometimes almost invisible and then with a rather thin tomentum.

Scapes 1-3, (0-)10-68 cm long, 1-5(-7) mm wide, villose or tomentose, hair colours as on the leaves. Involucral bracts 4-18 mm long, 0.5-3 mm wide. Dark capitular hairs rarely found on all vegetative parts.

Heads erect, obconical or with the base truncate, 10-25 mm long, 14-40 mm wide. Rays white above, pink, mauve, red or whitish-greenish below (rarely creamy or purplish on both sides) or bright yellow above, yellow and coppery below; tube 2.5-6 mm long, lower limb 6-24 mm long, 1-3 mm wide, upper limb 1-3 mm long, style 1.5-4.5 mm long. Disc florets white, yellow, reddish-purple, brown or black, tube 4-8 mm long, limbs 1-3 mm long, style up to 4 mm long; anthers often greenish or black.

Pappus violet, violet-purple, whitish or whitish-tawny to somewhat rufous, sometimes more or less two-coloured (violet-purple above, whitish below like in G. viridifolia ssp. viridifolia).

Achenes 5-9 mm long, pubescent-pilose, sometimes seemingly tapering, but usually protruding into a more or less distinct beak, 1-4 mm long.

Note: Rays which are white above and reddish below (with various shades) are confined to E. Cape, Natal, Orange Free State, Swaziland, Transvaal, and (fide Wild, 1972) Southern Mozambique. The yellow ray colour is universal in all other parts of the distribution area, but can also be found in the areas mentioned. The violet-purple pappus colour is similarly confined to the E. Cape-Transvaal area, while the whitish-tawny pappus is universal in all other areas, but also common in E. Cape-Transvaal.

Distribution: Gerbera Ambigua is found from around Humansdorp in the eastern Cape through Lesotho, Orange Free State, Natal, Swaziland, Transvaal\Mpumalanga, Mozambique to Tanzania; also in Rhodesia\Zimbabwe, Zambia, Malawi, Zaire, and Angola.

Ecology: Gerbera Ambigua grows in submontane areas or westwards on the plateaus, mainly from 200-2000 m a.s.l., but reaching the coast in Natal and the Eastern Cape in the south. In open woodland, on savanna, on slopes, in rocky soil, along roads, and in disturbed areas, on clayey soil, on marshy ground, along rivers, in ‘vlei’ or damp grassland, frequently in moister habitats than G. viridifolia.

Flowering time: Throughout the year.

When uniting Gerbera and Lasiopus, Schultz-Bipontinus (1844) proposed a new species, G. kraussii, closely allied to Gerbera Ambigua (Cass.) Schultz-Bip., tomentose on the lower surface, but with a rusty-white tomentum and distinctly raised nerves; the pappus colour was violet, not whitish, the rays yellow as in Gerbera Ambigua. Apparently quite distinct from G. ambigua, G. kraussii was generally accepted as a valid species for the next century.

Harvey (1865) separated Gerbera Ambigua into a narrowleaved form (G. discolor) and a broad-leaved form ( Gerbera Ambigua); Moore (1916) proposed a new species, G. welwitschii, with great affinity to G. ambigua, but collected in Angola and Malawi rather than the Cape. Thellung (1923) united G. ambigua and G. kraussii under the name Gerbera Ambigua with several varieties using the pappus colour as a diagnostic character; but he nevertheless stressed that as a distinguishing character this trait was rather artificial.

Thellung’s work remained ignored for forty years, and it was not until Jeffrey’s revision (1967b) that his ideas were revived. Jeffrey united all the species mentioned to one, G. ambigua; this concept was followed by Wild (1972). As already noticed, Hilliard (1977) rejected the importance of the leaf tomentum, re-establishing G. kraussii Schultz-Bip. while uniting G. ambigua (Cass.) Schultz-Bip. and G. viridifolia (DC.) Schultz-Bip. The diagnostic characters used by Hilliard appear from the table.

In many respects the variation in the ‘white tomentose complex’ parallels that discussed under G. viridifolia. As in this species several additional taxa have been proposed to account for the variation, but only G. discolor and G. welwitschii deserve attention.

The main problems in the complex are: 1) Is it possible to separate a taxon Gerbera Ambigua from a taxon G. kraussii using Hilliard’s proposals, and 2) can G. ambigua further be divided into a narrow-leaved form (G. discolor) and a broad-leaved form (G. ambigua s. str.)?

When using only the criteria nerves raised versus nerves not raised, and violet-purple pappus versus whitish pappus, 45% were found to be ‘G. kraussii-like’, about 33% ‘G. ambigua-like’ but at least 22% could not be placed with certainty in either of the groups.

Additional evidence against a distinction is: (1) The distribution of ‘G. kraussii’ sensu Hilliard was not identical with that of the specimens here referred to this group. Specimens having raised nerves or velvety upper leaf surface can be found all over the total area, but most often in the E. Cape-Transvaal range. (2) About one third of the specimens in the ‘G. kraussii-group’ was found to have whitish (-tawny) pappus colour, while the rest had violet-purple pappus or were more or less tinged with that colour. Identical plants from the same collection sometimes only differed in the pappus colour character. The pappus colour therefore has no taxonomic value. (3) The velvety upper leaf surface was quite frequent in specimens otherwise referable to the ‘ Gerbera Ambigua -group’. (4) Some specimens referred to the ‘Gerbera Ambigua -group’ deviated from it only by having raised nerves. (5) Specimens having winged petioles could be found anywhere in the material, although perhaps more commonly in the ‘G. kraussii-group’ than the ‘G. ambigua-group’. The decurrent lamina seems somewhat associated with ‘G. ambigua’ specimens with narrow leaves, but the variation is great. (6) Yellow rays were indeed rare in ‘G. kraussii’, but rays white above and red below were rather common in ‘G. ambigua’ (geographically related). Among the 22% not referable to any of the groups there was great variation.

In the ‘G. ambigua-like’ group no separation into a narrow-leaved and a broad-leaved form was possible, and G. discolor can therefore not be accepted as a separate taxon.

The conclusion is that only one taxon in this complex can be recognized. There are all kinds of transitional types between Gerbera Ambigua and Gerbera Krausii and no character combination can be found to sustain any separation of taxa.

However, several interesting distribution Gerbera Ambigua patterns can nevertheless easily be discerned: (1) Specimens with violet -purple pappus (or partly so) are confined to the Natal-Transvaal area (including Swaziland, Lesotho, and the Orange Free State), an area being surprisingly similar to that in which G. viridifolia ssp. viridifolia specimens with violet-purple pappus are found. The colour is usually found in specimens which are otherwise ‘G. kraussii-like’.

(2) The ray colours in the E. Cape, Lesotho, Orange-Free State, Natal, Swaziland, Transvaal area and, (fide Wild) rarely in Southern Mozambique, may be white above and red below (with variations) or yellow on both surfaces, but in any area north ofthese, the rays are always yellow (and the pappus light). This important fact seems to explain why Wild (1972) found that all Gerbera Ambigua had yellow rays – he only dealt with the Zambesiaca area, in which that colour is unique except in the extreme southernmost part. Hilliard, on the other hand, studied only the Natal-area, in which the variation is very great, and this may account for the different conclusions.

(3) In the Zambesiaca area, specimens with raised nerves below and/or velvety upper leaf surface are indeed limited in number, but can be found throughout the area; the G. we/witschii type specimens from Angola have the upper surface densely velvety tomentose, while the types from Rhodesia and Malawi have the upper surface almost glabrous. The many specimens used by Moore in the typification of G. we/witschii in fact reflect the entire variation very well!

Distinct Gerbera Ambigua – forms are rather common in the Natal-Transvaal area, growing side by side with the ‘G. kraussii-forms’. As in G. viridifolia the variation therefore is much more intricate here than north of the Lompopo river.

The five species in sect. Lasiopus seem to be closely related, separated only by a few morphological traits. There appears to be so much convergence and parallelism between the species that no conclusions can be given in respect to the phylogenetic relationships within the section.

Source: Opera Botanica 78 1985

Return to the top of Gerbera Ambigua