GrassBase - The Online World Grass Flora


W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Hygrochloa aquatica

HABIT Annual. Culms prostrate (floating); 100–200 cm long (long); spongy; rooting from lower nodes. Ligule a fringe of hairs. Leaf-blades floating; 4–16 cm long; 2.5–6 mm wide; mid-green and glaucous; discolorous with last colour beneath (glaucous above). Leaf-blade surface papillose; rough adaxially. Leaf-blade apex obtuse.

INFLORESCENCE Monoecious; with male and female spikelets in the same inflorescence. Inflorescence composed of racemes.

Racemes 5–10; borne along a central axis; distant; appressed; unilateral; 1 cm long; bearing few fertile spikelets; bearing 1–4 fertile spikelets on each. Central inflorescence axis 6–10 cm long; tip subulate. Rhachis angular; smooth on margins; terminating in a barren extension; extension subulate. Spikelet packing abaxial.

Sexes segregated; on unisexual branches; with male above. Spikelets solitary. Fertile spikelets sessile. Male spikelets sessile.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 2–2.75 mm long; falling entire.

GLUMES Glumes dissimilar; shorter than spikelet; thinner than fertile lemma. Lower glume orbicular; 0.5–0.75 mm long; 0.25 length of spikelet; membranous; without keels; 0 -veined. Lower glume lateral veins absent. Lower glume apex entire, or erose, or dentate; 2 -fid; obtuse. Upper glume ovate; 1.25–2.25 mm long; 0.66 length of spikelet; membranous; without keels; 5(–7) -veined. Upper glume apex entire, or lobed; 2 -fid; obtuse.

FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret ovate; 2–2.75 mm long; 1 length of spikelet; membranous; 5(–7) -veined; acute. Fertile florets female. Fertile lemma ovate; 2 mm long; coriaceous; much thinner on margins; without keel; 5 -veined. Lemma margins flat; covering most of palea. Lemma apex acute. Palea 1 length of lemma; coriaceous; 2 -veined.

FLOWER Anthers 3.

FRUIT Caryopsis with adherent pericarp; obovoid; dorsally compressed. Embryo 0.66 length of caryopsis. Hilum punctiform.

MALE Male spikelets distinct from female (in racemes bearing 1 spikelet); 2 flowered; separately deciduous; oblong; 3.5–4 mm long. Male spikelet glumes 2. Male spikelet lemma 5–7 -veined.

DISTRIBUTION Australasia: Australia.

NOTES Paniceae. WDC.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.