DUVALIAS IN SAUDI ARABIA
Sheila Collenette

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First published Asclepios, 78 (1999), pp 4-6
There are only three species of Duvalia in Saudi Arabia, all in the lowlands in the southwest of the country, with the altitude ranging between 200 ft and 2,500 ft.
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Two of them, D.sulcata var. semi-nuda and D.velutina are fairly abundant over quite a large range, with D.velutina extending the farthest north; it also has the most variation in the shape and colour of the flowers which range from a dusky rose-pink to greenish-red to green.

Duvalia sulcata
Left: From the Al Abna descent. Right: From between Sabiya and Jabal Fayfa

I believe a recent revision of the group has assigned the form of D.sulcata in Saudi Arabia to conspecific rank with the variety semi-nuda. I prefer to leave things as they were, for apart from the presence or absence of hairs on the annulus, the colour of D.sulcata is always a flesh-pink and the lobes are usually wider; the variety semi-nuda is a deep purplish-red with, very occasionally, one or two hairs on the annulus. As can be seen from the illustrations, D.sulcata occasionally has a creamy, angled corona and then the flowers have narrower lobes. D.sulcata is relatively rare, being found in only three widely scattered populations; among the westem foothills at the base of Jabal Fayfa; between Sabiya and Jabal Fayfa, and partway down the Al Abna descent, 25 km from its junction with the Jiddab--Jizan road at Namrah. The mottled soft-spiny grey-green stems form large clumps, and the short flower stems arise from near the centre or base of a stem. The plants prefer a well drained granite soil, though they can tolerate sandier conditions if there are no choking grasses around the clumps; they lurk in the shade of shrubs such as Anisotes trisulcus or small bushy acacias, especially A.oerfota. The flowers are usually 2.5 cm wide.

Duvalia sulcata var semi-nuda
Left: From near Huhayl. Right: Another specimen (#1991) in bud, also from near Huhayl.

D.sulcata var. semi-nuda is perhaps the most common. It can be found in widely scattered localities, from near Ad Aridah, near the Yemen border and along the road to Abu Arish, near Al Hagu, around Muhayl, along the Muhayl--Mudhaylif road as far as Namrah, and along several kilometers of the lower part of the Al Abna Descent. It is always to be found under shrubs and I have never seen it in grass tufts, unlike D.velutina; it can tolerate a variety of sandy or gravelly soils and can form wide carpets which, at the right moment, can carry many flowers. Only once have I seen flowers that were not a shiny purplish-red, and that was in a population adjacent to a clump of D.sulcata; perhaps hybrids. The flowers, usually 2.5 cm wide, are carried on a short pedicel with two or three flowers opening in succession from a single growing point; the stems are short and plump and have a long curved narrow base. The buds are a pointed pyramid shape and this immediately distinguishes them from those of D.velutina when the plants have no open flowers.

Duvalia velutina
Above left: From Jabal Marshid. #2726 (Photo: John Higginbottom).
Above right: From Al Khudais.
Below: From Jabal Shada. Right From near Al Hagu.

D.velutina was described as a new species by John Lavranos when he found it in 1980 growing at Hakima, near the Agricultural Station, together with D.sulcata var. semi-nuda. The commonest colour form has rather flat reddish-green flowers, usually 2 cm in diameter, and with fairly wide ridged lobes and the whole flower is covered with a pubescence of soft hairs; the strikingly two-coloured flowers from plants from the base of Jabal Shada are 3.2 cm wide. The buds are rounded and the pedicels, usually twice as long as those of D.sulcata var. semi-nuda, arise from near the base of fairly long erect stems. Although not very common it has a wide range, from near Al Hagu, to Hakima and on to Adam; its habitats include the shade of shrubs, even small ones like Indigofera spinosa, and thick grass tufts, so it is not surprising that there should be a variety of shapes and colours. Those plants from grass tufts on the coastal plain, between Ad Darb and Sabiya and near Jabal Marshid, have rounded flowers with short lobes, whereas those from Al Khudeis, 40 km south of Namrah have green flowers with narrow lobes, similar to many of the African species. Unfortunately that population has disappeared through scrub clearance for housing. It appears to be endemic to Saudi Arabia though it is possible it will turn up on the Tihama of northern Yemen.

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