Sphenocleaceae
S.M.H. JAFRI
Herbarium, Department of Botany
University of Karachi, Karachi.
Semiaquatic annual herbs, glabrous, erect or suberect, somewhat succulent with spongy tissue. Leaves simple, exstipulate, alternate, lanceolate or elliptic, entire. Inflorescence terminal, a dense cylindric spike. Flowers small, sessile, bracteate, regular, complete; bract 1; bracteoles 2. Calyx 5-lobed; tube short and adnate to the ovary; lobes imbricate, persistent, ovate. Corolla perigynous, 5-lobed, imbricate, campanulate-urceolate, caducous. Stamens 5, alternating with the petals, inserted on the corolla tube; filaments short with rounded 2-celled anthers. Ovary semi-inferior, bilocular; style short with capitate sub-bilobed stigma; ovules numerous on axile placenta, anatropous. Capsule (pyxidium) short, obconic, membranous, 2-locular with circumscissile dehiscence at the level of the calyx-lobes; seeds numerous, minute, oblong, with irregularly plicate-costate testa, almost exalbuminous; embryo straight, subterete.
A pantropical family with a single genus and 2 species. It is represented by only 1 species in W. Pakistan.
The family was first recognized by Lindley (Nat. Syst., 2:233:1836) but most of the later authors, including Bentham and Hooker and Engler & Prantl included it in the Campanulaceae. However, DeCandolle (Prodr., 8:548.1839) and Boissier (FI.Or.,3:963.1875) followed Lindley. Though Hutchinson (Families, Dicots. 1926;) did not separate it from Campanulaceae but Airy Shaw (Fl. Malesiana, 4:27.1948) strongly advocated for its separate identity, drawing relationship with Phytolaccaceae and Primulaceae with a remark that the family represented a half-way house between these two. F.N. Happer (Fl. West Trop. Africa, 2:307.1963) has rightly pointed out that this family is not allied to Phytolaccaceae (although has superficial morphological resemblance) but is intermediate between Campanulaceae and Primulaceae and has sufficient justification for its separate identity. It is separable from Campanulaceae by its circumscissile capsule and imbricate corolla lobes on the regular flowers. It differs from Primulaceae by its spiked inflorescence, minute flowers with stamens alternating with the petals, ovary semi-inferior and bilocular.
Acknowledgement: We are grateful to the United States Department of Agriculture for financing this research under P.L. 480.
