Studies in the Hypoxidaceae. III. The genus Pauridia

The genus Pauridia is revised and two species are recognized: P. minuta (L.f.) Dur. & Schinz and P. longituba M. F. Thompson. Line drawings, distribution maps and scanning electron micrographs of the pollen are included.

Pauridia minuta occurs mainly on flats and lower slopes in clayey sandy-loam soils between Saldanha Bay and Riversdale extending inland to Ceres (Fig. 1, map 1).There is considerable variation in leaf width in P. minuta from a filiform (c. 1 mm) semi-terete form (Fig. 2a, h) to a broad (5 mm wide) carinate form (Fig. 2c, g).The forms grade into one another and do not appear to be linked to the distribution or to other characters.I do not consider the forms to be of varietal status.The arrangement of the vascular bundles in the filiform type is not like that of the truly terete leaf of other Hypoxidaceae (Thompson, 1976).Even in the narrowest leaf there is a large keel-bundle with at least one small bundle on either side (Fig. 2h).
In 1833 N. E. Brown described the variety, P. minuta var.muirii, from the Riversdale District, stating that it " seems to differ from the type only in its smaller size and more eastern locality" .Similar plants (Fig. 2b) have been found in the Malmesbury District (Thompson 103, 3814, Strauss 102), while in the Caledon District equally small plants, but with broader leaves occur (Compton 10677, Lewis 3022).I do not recognize the variety as the locality is not confined to the Riversdale District and the size is probably a reflection of the habitat.
Where the species occurs in shallow pockets on •rock surfaces (Compton 18000, Thompson 21B, 93, 278, 3816, 3818) the leaves are longer than the scape at the time of flowering.In fruit the bend at the node  between the peduncle and pedicel is not as angular as usual, but rather forms a sharp curve.The upward curve below the fruit is more marked giving the scape a curled or sigmoid appearance.This may be due to the fleshy nature of the scape in wet conditions.The shallow pockets are generally water-logged during the winter growing season, but completely dry in summer.
The pollen in P. minuta appears to vary from an ellipsoidal, regularly 2-sulcate grain (Fig. 3a) to a spheroidal shape with irregular sulci (Fig. 3b, c).These variations are not correlated with size or leaf width.Erdtman (1952) records 1-sulcate grains for the Hypoxideae.Further details and comparisons of pollen within the family will be given in a later paper.
Corm globose, about 6-7 mm in diam., covered with rigid reticulate fibres.Leaves included in a sheath, glabrous, linear-canaliculte, ± 1 mm wide, over-topping the flowers.Peduncles many, oneflowered, short.Pedicel very short, 0-2 mm long.Bracts two, opposite, setaceous, unequal, longer than the pedicel, the longer up to 10 mm long.Flowers regular, white; perianth tube narrow cylindric, 8-30 mm long; lobes spreading l/3-± the length of the tube, ovate-lanceolate, subacute, the inner slightly smaller.Stamens three, inserted in the throat of the perianth-tube opposite the inner segments; filaments short 0 ,4 -1 ,5 mm; anthers basifixed, 1,5-2,75 mm long, 2-thecous, splitting longitudinally.Ovary ovoid, 3-locular, placentation axile, ovules numerous in each chamber; style slightly shorter than the perianth tube; stigma up to 5 mm long, 6-lobed, three long connate lobes and three small appendages at the base.Fruit indehiscent, often partially enclosed in the leaf sheaths.Vegetatively P. longituba is very similar to forms of P. minuta.The cross section of the leaf is like that of the terete form (Fig. 4a, b).Apart from the obvious modifications connected with the elongation of the perianth tube and style (Fig. 4c, d), the floral vascular anatomy is like that of P. minuta (Thompson, 1978).
Pauridia longituba is restricted to the granite outcrops, which are characteristic of the Vredenburg/ St Helena Bay area.The plants occur only in pockets of soil on the rocks and I have never found any in the deeper soils around the lower edges of the boulders.The plants and flowers vary in size depending on the amount of soil in the pockets.
Although not restricted to the granite, P. minuta can occur in similar habitats in the Langebaan area.At only one known locality do the two species occur together (Thompson 21A, 21B).In this habitat, the P. minuta plants are of the form mentioned under that species, but no intermediates between the two species were found.
The pollen grains are slightly larger than those of P. minuta.The two sulci are wide set (Fig. 5a).The surface is irregularly granular-pitted and even on acetolysis does not show distinct sculpturing (Fig. 5b).