Bolboschoenus (Asch.) Palla (Palla 1905: 2531)

Rasaminirina, Fitiavana & Larridon, Isabel, 2023, The genera of Cyperaceae of Madagascar, Plant Ecology and Evolution 156 (3), pp. 276-310 : 276

Bolboschoenus (Asch.) Palla (Palla 1905: 2531)

Type species.

Bolboschoenus maritimus (L.) Palla

Description of the genus.

Perennials with long rhizomes often forming hard ovoid tubers at tips. Culms many-noded, sharply trigonous, thickened at base. Leaves basal and cauline, eligulate; blade often reduced in lower leaves. Involucral bracts leaf-like, patent, lowermost often suberect. Inflorescence terminal (in reduced inflorescences, bract may be erect, but clearly leaf-like), a (compound) corymb-like anthela or capitate with 1-many spikelets. Spikelets with many spirally arranged, deciduous glumes, each subtending a flower. Glumes puberulent, the apex entire to emarginate or deeply 2-fid, awned or mucronate. Floret bisexual. Perianth present, formed by 3-6 parts, shorter to longer than the nutlet, bristle-like, deciduous with fruit. Stamens 3. Style 2-3-fid; base persistent, barely thickened. Nutlets obovate, dorsiventrally lenticular or trigonous. Pericarp with the three highly differentiated layers, exocarp cells often enlarged and hollow; surface smooth, epidermal cells roughly isodiametric. Embryo fungiform with three primordial leaves.

Distribution and ecology.

Bolboschoenus is a cosmopolitan genus ( POWO 2022). It grows in saline, brackish, or freshwater wetlands. In Madagascar, Bolboschoenus is known from the north and west, occurring in the Diana Region of Antsiranana province, Boeny region of Mahajanga province, and Atsimo Andrefana region of Toliara province. Only a single species occurs in Madagascar, i.e. Bolboschoenus glaucus (Lam.) S.G.Sm. (Fig. 18 ).

Figures

Figure 18. Bolboschoenus glaucus. A. Habit. B. Inflorescence and leaves. C. Leaf sheath apex. D. Spikelet. E. Anther. F. Ovary, style and branches. G, H. Glume, adaxial and abaxial surface. I. Glume apex. J. Nutlet, abaxial view. K, L. nutlet sections. All from van Rensburg 2404. Scale bars: A = 250 mm; B = 10 mm; C = 40 mm; D-K = 2 mm. Abbreviations: ex = exocarp, m = mesocarp, en = endocarp. Drawn by Jane Browning, reproduced with permission from the artist, originally published in Browning et al. (2020).