A new species of Putterlickia (Celastraceae) from southern Natal and Pondoland

S.C


Introduction
The genus Putterlickia End!. is confined to southern Africa and comprises a variable assemblage of closely related forms. H is distinguished from May tenus Molina essentially by having (4 -)6 -8( -10) ovules compared to two per locule, with the placentation axile and axile-basal respectively. Despite the apparent lack of marked differentiating characters, two species of doubtful distinction, namely P. pyracantha (L.) End!. and P. verrucosa (E. Mey. ex Sond.) Szyszy!., have been recognized in recent years. Current work on the group has now confirmed the specific status of at least one clearly circumscribed infrageneric taxon. In the present paper this long recognized but hitherto unnamed species is formally described.
Flowering mainly October -December. Fruits usually ripening between January and April.

Distribution
Putterlickia retrospinosa is a forest climber endemic to the southern NatallPondoland sandstone (Natal Group) region ( Figure ·2). The species usually grows in rocky places and is found mainly along forest margins (particularly those in exposed situations) and in short shrub forest. It is fairly common throughout most of the sandstone region and therefore is a useful indicator species for the flora of this wellknown centre of endemism.
Putterlickia verrucosa has been recorded from the areas surrounding the southern Natal/Pondoland sandstone 'island'. The distribution range of P. retrospinosa therefore falls within the range of P. verrucosa but, curiously, the two species are mutually exclusive without any evidence of c1inal variation or introgression.

Discussion
Putterlickia retrospinosa is a distinctive and easily recognized species. It seems to be most closely allied to P. verrucosa which also has abundant prominent whitish lenticels on the stems. Diagnostic characters include its exclusively climbing habit, reflexed spines, entire margined and broadly elliptic to broadly obovate leaves which are the largest in the genus, and relatively large inflorescences. P. verrucosa and P. pyracantha are usually shrubs or small trees, although the former species may occasionally assume a somewhat scandent habit, particularly in northern Natal. In both these species the spines are slightly apically directed or arranged more or less perpendicular to the stem axis and the relatively small leaves are usually obovate to oblanceolate-spathulate. In addition, the blade margin is often spinulose-denticulate, particularly in P. verrucosa.

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The specific epithet of the new species refers to the distinctive backward-pointing spinescent branches which are particularly well developed on older stems. These spines are clearly an adaptation to the climbing habit of the species. Plants are very sparsely branched and once out in the light, sprawl across shrubs and trees in a straggling manner. Ultimate branchlets occasionally display much smaller and even, more or less perpendicular spines, or may be spineless. In the absence of support, the stems are usually procumbent. All plants observed in the field were clearly not shrubby or tree-like as described by Coates Palgrave (1977)  It has been widely claimed that Putterlickia is characterized by up to six (more rarely reduced to three or perhaps two) ovules per locule (Davison 1927;Loesener 1942;Robson 1965Robson , 1966. The present study has shown that P. retrospinosa contains (6 -)8 -10 ovules per locule. Up to eight (rarely ten) ovules per locule have also been found in forms falling within the concept of P. pyracantha and P. verrucosa. Six ovules per locule nevertheless seem to be the prevailing state over most of the distribution range of the genus. This also applies to the small-leaved Karoo form which, under the name Gymnosporia saxatilis (Burch.) Davison, was described as having two ovules per locule (Davison 1927). Reduction of ovule number to five or four per locule has so rarely been encountered that figures of less than six ovules per locule should be considered aberrant.