Hydrochloa P. Beauv.
From the Greek hudor (water) and chloa (grass), alluding to habitat.
Sometimes referred to Luziola (L. fluitans, = H. caroliensis
Habit, vegetative morphology. Perennial; a slender aquatic, floating or with trailing culms 30–100 cm long. Culms herbaceous; branched above. Leaves not basally aggregated; with auricular setae (usually 2 or 3 on either side). Leaf blades narrow; 2–5 mm wide (by 2–6 cm long); flat; an unfringed membrane; 0.5–1 mm long.
Reproductive organization. Plants monoecious with all the fertile spikelets unisexual; without hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; female-only and male-only. The male and female-fertile spikelets in different inflorescences (male spikelets in small few-flowered terminal panicles or racemes, female spikelets axillary, solitary or in few-flowered racemes). The spikelets overtly heteromorphic.
Inflorescence. Inflorescence reduced to a single spikelet, or few spikeleted; a single raceme, or paniculate; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent.
Female-sterile spikelets. Male spikelets about 4 mm long, 1-flowered, the lemma thin and 7-nerved the palea thin and 2-nerved, the floret with 6 free stamens. The male spikelets without glumes; 1 floreted. Male florets 6 staminate. The staminal filaments free.
Female-fertile spikelets. Spikelets unconventional (through lacking organs, presumably glumes); 2 mm long; not noticeably compressed to compressed dorsiventrally; abscising below the spikelet. Rachilla terminated by a female-fertile floret.
Glumes absent. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas not becoming indurated (thin); entire; pointed; hairless; without a germination flap; 5–7 nerved. Palea present; relatively long (thin); not indurated; several nerved (4–7); one-keeled. Stamens 0. Styles fused (?). Stigmas 2 (long).
Fruit, embryo and seedling. Pericarp fused.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal. Intercostal papillae complex - one large papilla on each long-cell and interstomatal, itself covered by the numerous, minute papillae which extend over most of the cell surface. Long-cells markedly different in shape costally and intercostally (the costals much narrower and more regular); of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells irregular, but rectangular; having markedly sinuous walls. Microhairs present (detectable by the bases, but hard to locate and none seen in good condition); ostensibly one-celled (cf. Luziola?); minute. Stomata fairly common (in single files near the costal zones); 18–21 microns long. Subsidiaries often papillate (two papillae each, near their ends). Guard-cells deeply sunken amongst the surrounding papillate cells. Intercostal short-cells common; silicified. Intercostal silica bodies oryzoid-type. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; exclusively dumb-bell shaped (short).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade; probably with arm cells (but the material seen very poor); without fusoids. Midrib fairly conspicuous (by its larger bundle); with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups (a large group in each intercostal zone); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 12. 2n = 24.
Taxonomy. Bambusoideae; Oryzodae; Oryzeae.
Distribution, ecology, phytogeography. 1 species; southeast U.S.A. Hydrophytic.
Holarctic. Boreal. Atlantic North American. Southern Atlantic North American.
References, etc. Leaf anatomical: this project.
Special comments. Fruit data wanting.
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).