PACHYPODIUM SAUNDERSII.
Transvaal, Swaziland.
Apocynaceae. Tribe Echitideae.
Pachypodium, Lindl.; Benth. et Hook. f. Gen. Plant. vol. ii. p. 722.
Pachypodium Saundersii, N. E. Br. in Kew Bulletin 1892, 126; Fl. Cap.
vol. iv. sect. i. p. 516.
It is with pleasure that we figure for the first time this species of Pachypodium, which flowered at the Division of Botany, Pretoria, in 1923, from tubers forwarded by Mr. J. Kirton, Pietersburg, Transvaal. The genus Pachypodium differs from Adenium (see Plate 16) in having a pair of spines at the base of the leaves, but the present species agrees with Adenium multiflorum in its general habit. Both have large succulent stems, partly below the ground, from which the branches arise. In Pachypodium Saundersii the pollination mechanism is somewhat complicated, but in what way the various structures function in this is not quite clear. The flowers are protandrous and the anthers all converge to a point. The base of the anther is provided with a pouch and the filament with a ciliated hood, and these two structures form a cage for the pollen. The stigma lies within this cage, and the style may possibly elongate eventually, and thus push the pollen above the anthers, as in the Compositae. The plant flowered freely in Pretoria, but failed to fruit, and from this it may be assumed that self-pollination does not take place.
Description:—Inflorescence arising in an umbellate manner at apex of stems, up to 11-flowered. Sepals 4 mm. long, 3·5 mm. broad, ovate, acuminate, acute, glabrous. Corolla-tube 3·5 cm. long, cylindric and 1·2 cm. long below, with a subglobose base, then suddenly dilated and narrowed towards the apex, glabrous without, pilose within; lobes 2·2 cm. long, 1·8 cm. broad in the widest part, straight on[{16}] one side, very convex and crisped on opposite side, subacuminate, acute. Filament 3 mm. long, 2 mm. broad, ovate, with a ciliated hood at the base; anthers 6·7 mm. long, linear with a lanceolate, acute appendage 1·5 mm. long, and a membranous pouch at the base. Style 1·3 cm. long, terete, glabrous; stigma club-shaped covered with a white opaque jelly-like substance; ovary 3·5 mm. long, with a cupular disk at the base (National Herb. 2736).
Plate 123.—Fig. 1, median longitudinal section of the flower; Fig. 2, stamen; Fig. 3, portion of style with the stigma; Fig. 4, the 2 carpels with a cupular disk at the base.