Grass Genera of the World

L. Watson and M. J. Dallwitz


Dielsiochloa Pilger

Habit, vegetative morphology. Perennial; caespitose. Culms herbaceous. Leaves non-auriculate (?). Leaf blades narrow; setaceous; without cross venation; an unfringed membrane.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.

Inflorescence. Inflorescence paniculate; oblong, contracted; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets compressed laterally; disarticulating above the glumes; not disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.

Glumes two; very unequal; shorter than the adjacent lemmas; pointed; awnless; carinate. Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 4–7; clearly specialised and modified in form; awned (the prominent awns of the sterile lemmas apparently functioning to aid disperal). Spikelets without proximal incomplete florets.

Female-fertile florets 2–3(–4). Lemmas firmly membranous; incised; 2 lobed; awned. Awns 1; median; dorsal; from near the top, or from well down the back; non-geniculate. Lemmas hairless; carinate to non-carinate; without a germination flap; 5 nerved. Palea present; gaping; 2-nerved. Lodicules present; 2; free; membranous; glabrous; toothed; not or scarcely vascularized. Stamens 2–3. Ovary glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small, or medium sized (4 mm long); compressed dorsiventrally. Hilum long-linear. Embryo small. Endosperm hard; containing compound starch grains.

Abaxial leaf blade epidermis. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much smaller and narrower); of similar wall thickness costally and intercostally (walls thick, pitted). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata absent or very rare (present in the furrows adaxially - with parallel-sided subsidiaries). Intercostal short-cells absent or very rare. Thick walled prickles common costally. Crown cells absent. Costal silica bodies poorly developed; perhaps tall-and-narrow, or crescentic, or poorly developed in material seen.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms unclear in the poor material seen. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent (some bundles with an abaxial strand only, others with a small adaxial strand as well). Sclerenchyma all associated with vascular bundles (except at the blade margins).

Taxonomy. Pooideae; Poodae; Aveneae.

Distribution, ecology, phytogeography. 1 species; Peru. Species of open habitats. In high altitude grassland.

Neotropical. Caribbean and Andean.

References, etc. Leaf anatomical: this project.


Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘Grass Genera of the World: Descriptions, Illustrations, Identification, and Information Retrieval; including Synonyms, Morphology, Anatomy, Physiology, Phytochemistry, Cytology, Classification, Pathogens, World and Local Distribution, and References.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).

Index