The subspecies of Pelargonium cucullatum ( Geraniaceae ) *

Pelargonium cucullatum (L.) L’Herit. is shown to consist of three infraspecific taxa, which are given subspecific ranking under the names P. cucullatum subsp. cucullatum, subsp. tabulare Volschenk and subsp. strigifolium Volschenk. It is also shown that P. angulosum (Mill.) L’Herit. (Geranium angulosum Mill.) is synonymous with P. cucullatum subsp. cucullatum, but that the name P. angulosum has been misapplied for many years to subsp. strigifolium. The latter was formerly known as P. acerifolium L’Herit., non Geranium acerifolium Cav. Pelargonium cucullatum (L.) L’Herit. is a conspicuous and well-known species. It was first collected in 1672 by the Dutch botanist Paul Hermann of Leiden, probably on the slopes of Table Mountain where it is still abundant. The first record of its introduction into cultivation in England was that of Bentick in 1690. Harvey (1860) reported that it was used for ornamental hedgerows in Cape Town during his stay from 1838 to 1840. Horticulturally it is an important species which has been used extensively in hybridization, especially in the breeding of the ‘regal’ cultivars. The identity and circumscription of P. cucullatum is important, as Van der Walt (1979) designated it as the lectotype species of the genus Pelargonium. P. cucullatum in its original circumscription consisted of two taxa. The first taxon has leaves which are dentate but not incised and grows against the north-western, western and southern slopes of the Cape Peninsula as well as near Saldanha Bay. The second taxon has angularly incised leaves and occurs on the eastern side of the Cape Peninsula, on the eastern side of False Bay, and eastwards along the coast as far as the vicinity of Gansbaai. It always grows close to the beach. In both taxa the leaves are villous and soft to the touch. It was found that a third taxon, P. acerifolium L'Herit. (commonly but erroneously known as P. angulosum), has such a close morphological resemblance to P. cucullatum that we do not consider it justified to afford them separate specific status. In this taxon the leaves are angularly incised, strigose and harsh to the touch. No structural differences could be detected between the flowers of the three taxa although the petals of P. acerifolium are often light pink instead of pinkish purple. As can be expected from the different textures of the indumentum, there is a difference in the shape of the individual trichomes on the leaves. Hence in P. acerifolium the trichomes are relatively short, broad-based and curved, whereas in the other two taxa the trichomes are conspicuously long, slender and straight. A complete anatomical study was made of the young stems, petioles and laminae. The only differences that we noted between the three taxa are the presence of a central fibrous column in the central vascular bundle of the petiole of the first two ’Forms part of an M.Sc. thesis submitted by the first-named author to the University of Stellenbosch. * * All Department of Botany, University of Stellenbosch, Stellenbosch. 7600. taxa enumerated above (but absent in the third); and the arrangement of the guard cells of the stomata which are raised above the surface of the epidermis in the first two taxa, but are level with the surface of the epidermis in the third taxon. We also examined the pollen grains of all three taxa with a lightand a scanning electron microscope, but could detect no difference between

taxa enumerated above (but absent in the third); and the arrangement of the guard cells of the stomata which are raised above the surface of the epidermis in the first two taxa, but are level with the surface of the epidermis in the third taxon.
We also examined the pollen grains of all three taxa with a light-and a scanning electron microscope, but could detect no difference between them.
Cuttings as well as field-collected seed of all three taxa were grown side-by-side in Stellenbosch to determine whether the differences which we observed were environmentally induced.We found that the plants retained their respective characters under these conditions.From this we conclude that the differences are genetically fixed.
It is our considered opinion that the degree of morphological similarity between the three taxa is of such a magnitude that we must regard them as conspecific.Nevertheless the differences in leaf shape and indumentum are striking, and are linked to an allopatric distribution which suggests a high degree of spatial genetical isolation between them.For these reasons we regard them as three separate subspecies of the same species to which the name P. cucullatum applies.
We interpret Linnaeus's original description as follows.Firstly, that the epithet cucullatum sensu stricto applies to the beach-hugging subspecies with incised, villous leaves.Secondly, that the subspecies with dentate, non-incised, villous leaves, found against the western, north-western and southern slopes on the Cape Peninsula be designated subsp.tabulare Volschenk.and finally that the former P. acerifolium be given a new name, subsp.strigifolium Volschenk.
The total combined distribution range of the three subspecies does not exceed about 220 km from west to east, and the three subspecies at places occur in close proximity to one another.It may seem unusual for three subspecies to occur in such a small area, but we would like to point out that this area is well-known for the the diversity of its flora.It is a mountainous area with deep intervening valleys in a region where great differences in climate and environmental conditions occur over short distances.This rugged topography provides effective barriers against migration and gene flow.Thus subsp.cucullatum occurs in cool situations near the beach mostly against east-or south-facing slopes (but west-facing immediately east of False Bay), on sandy and well-drained soil under a rainfall regime of 400-800 mm per annum.Subsp.tabulare occurs under a range of environmental conditions, from the dry, hot, west-facing slopes on the Cape Peninsula to cool moist conditions towards the tip of the Peninsula and on its east-facing slopes with an annual rainfall varying from 200 to 1 000 mm.The environmental conditions at Saldanha Bay where this subspecies also grows are probably more or less similar to those on the Cape Peninsula.Our impression is that subsp.tabulare can exist under conditions as moist as those under which subsp.cucullatum thrives, but that it can also survive in much hotter and drier situations.It occurs from near the beach to altitudes as high as 500 m.Subsp.strigifolium is essentialy montane and occurs further inland at altitudes of 300-900 m, experiencing an annual rainfall of 600-1 000 mm per annum.It is found on a variety of soils derived from sandstone, shale, tillite, granite and granofir, and plants experiencing the lower end of the rainfall range are often found on heavy soils.Whereas the habitat of subsp.strigifolium can become very wet during the winter months, it is drier during summer than the habitats of either subsp.cucullatum or subsp.tabulare, where the air is moist throughout the year due to their close proximity to the sea.All three subspecies occur in fynbos.
The present-day distribution areas of the three subspecies are not all continuous (Fig. 1).The main concentration of subsp.cucullatum is east of False Bay, but a few populations also occur on the Peninsula immediately west of False Bay but separated by a distance of about 35 km.This is not much, but as this subspecies is conspicuously absent  The seeds of P. cucullatum are dispersed by wind, but their aerodynamic properties are such that it is unlikely that they are spread more than a few metres from the parent plant.For this reason it seems probable that the disjunct concentrations of the three subspecies are relics from a former much wider distribution.This is supported by evidence of past climatic fluctuations cited below.
Investigations by Brain & Meester (1964) indicated that the pattern of rainfall changes in southern Africa followed a cyclical sequence since the Plio-Pleistocene (1-2 million years ago) with three wet periods (pluvials) during which the rainfall may have been 150% higher than at present.It is conceivable that during one or more of these pluvials, conditions were moist enough along the west coast to enable subsp.tabulare to occupy a continuous area between Cape Point and Saldanha Bay.During the inter-pluvial this subspecies would have died out in the intervening area with only the present two relic populations surviving where conditions were still favourable for its continued existence.The same hypothesis could explain the present disjunct distribution of subsp.cucullatum, with the break in distribution afforded by the drier Cape Flats; as well as the confinement of subsp.strigifolium to mountainous areas, moister than the intervening areas.It is possible that during a pluvial the intervening areas were moist enough for the subsp.strigifolium to occupy a continuous area, but that when it became drier and conditions at lower altitudes became unsuitable for the survival of this subspecies, populations were left stranded on isolated masses of higher land.The environmental differences experienced by the three subspecies, and even more so their environmental requirements, are still imperfectly understood, and much data remain to be gathered.All three appear to be quite adaptable when cultivated, and the restricted nature of their natural environment is perhaps to be sought in subtle moisture differences affecting seed germination.
Erect, perennial shrub, 1 -2 m high, with a taproot system and a series of underground runners giving rise to aerial shoots at intervals.Branches herbaceous, becoming woody at base with age, 6 -1 0 mm in diameter, sparsely to densely pubescent to villous, beset with glandular hairs, green but turning brown with age.Leaves crowded at ends of branches, alternate, simple, petiolate; lamina (2 0 -)

Diagnostic features
Lamina sightly to strongly hood-shaped, shallow ly and angularly incised in distal half, base obtusely subcordately to cuneately incised, villous; petiole usually shorter than lamina, with a central fibrous column present in the central vascular bundle.Pseudo-umbels with 5 -7 flowers each.Petals usually dark pinkish purple, occasionally white.(Fig. 3).

Geographical distribution and habitat
The subsp.cucullatum has a small, continuous distribution from the vicinity of Gansbaai in the east to Gordon's Bay in the west, with a few isolated populations in the Cape Peninsula which are separated from the rest by False Bay.The leaves of the plants on the peninsula are less villous than elsewhere.The plants occur from near the high water mark on the narrow coastal flats and in the lower foothills of the mountains, but always practically within sight of the sea (Fig. 1).
The subsp.cucullatum is a constituent of moist coastal fynbos.It occurs under rainfall regime of 400-800 mm per annum, on well-drained, sandy soils which are mainly derived from Table Mountain Sandstone.
Flowering takes place from September to February.The impression was gained that individual plants of this subspecies have a longer flowering period than the subsp.tabulare, and this may be ascribed to the moister, perhaps more favourable environmental conditions experienced by the subsp.cucullatum.

Taxonomic notes
Our interpretation of Linnaeus's concept of Geranium cucullatum is based on the following sources which were available from the original description in L., Sp.PI. edn 1: 677 (1753): 1. Linnaeus's description (GERANIUM calycibus monophyllis, foliis cucullatis dentatis).This is insufficient to distinguish from one another the three subspecies recognized in the present treatment.

Geographical distribution and habitat
The subsp.tabulare occurs in two relatively restricted areas separated from each other by a distance of about 90 km; namely on the Cape Peninsula where it ranges from Lion's Head and Table Mountain southwards to Cape Point, and in the vicinity of Saldanha Bay (Fig. 1).On the Cape Peninsula it occurs as a component of fynbos, from sea level to about 500 m against the mountain slopes, but always practically within sight of the sea.It grows on well-drained, usually stony and often sandy soils derived from Table Mountain Sandstone It should be noted that the Saldanha Bay plants are smaller than those on the Cape Peninsula, especially in respect of the leaves and flowers, but this appears to be a result of less favourable environmental conditions and is not of taxonomic significance.
The flowering period stretches from late Septem ber to February, with a peak in October and November.

Diagnostic features
Lamina flat to somewhat hood-shaped, shallowly and angularly incised in distal half, base cuneately incised, strigose and with glandular hairs longer than ordinary hairs; petiole usually shorter than lamina, with a central fibrous column absent (rarely present) in the central vascular bundle.Pseudo-umbels with 3 -5 flowers each.Petals usually light pink to pinkish purple.Fig. 7.

Geographical distribution and habitat
The subsp.strigifolium has a montane distribu tion in the south-western Cape Province, being known from the mountains around Bainskloof in the north to Baardskeerdersbos in the south, and the southern Hottentotsfiolland Mountains in the west to the Kleinrivier Mountains near Caledon in the east, at altitudes of 300-900 m.In contrast to the subspecies cucullatum and tabulare} this subspecies does not occur in close proximity to the sea.
Like the other two subspecies, it is a constituent of fynbos.Few precise rainfall figures are available for its montane habitats, but the rainfall over the general area varies from about 600 to 1 000 mm per annum.It grows on soils derived from sandstone, shale and tillite, and in the vicinity of Paarl and Jonkershoek also on soils derived from granite and granofir.These soils can be quite heavy.
Plants from the Swartberg near Caledon are smaller than elsewhere, probably occurring under less than optimal conditions at the eastern border of

Taxonomic notes
We chose a completely new epithet for this subspecies, to avoid possible future confusion between the names Pelargonium acerifolium L'H6rit.(which is superseded by the new name P. cucullatum subsp.strigifolium) and Geranium acerifolium Cav.Although this does not preserve continuity of epithet, it is permissible under Article 11.3 (ICBN, 1978), which states that an epithet has priority only within its own rank.
Pelargonium acerifolium L'Herit.( 1789) is not considered to be a recombination based on Geranium acerifolium Cav. ( 1787), but rather as a different name, because L'Heritier made no direct or indirect reference to Cavanilles and actually was concerned with a different taxon.
, shale and tillite.It receives an annual rainfall of 400-1 000 mm on the Cape Peninsula.In the Saldanha Bay area it occurs in fynbos vegetation in sheltered ravines, under conditions somewhat reminiscent of those on the Cape Peninsula, but receiving only about 200 mm of rain per annum.