keys to the vascular plants of east texas - Botanical Research ...

ZIZANIOPSIS/POACEAE 1103
(1999) (possibly as a result of misidentification of Z. texana, as in the erroneous on-line listing
of a Healley collection from Hays Co. at TAES—Digital Flora of Texas Herbarium Specimen
Browser 2002); however, we have seen no TX material and recent taxonomic treatments of
North American Zizania (Terrell et al. 1997; Terrell ined.) give the distribution of this species as
extending from s Canada and the e U.S. w only to sw LA. We are including the species because
of the possibility of its occurrence and to encourage field botanists to look for it in TX; no
county distribution map is provided. Jun–Nov. Breeding of this species (long gathered from
wild stands) is “yielding non-shattering forms of potential economic importance” (Watson &
Dallwitz 1992). Such forms exhibit retention of the seeds on the inflorescence and thus less loss
of the grain crop; similar situations (presumably the result of artificial selection) can be seen in
corn, sunflower, and many other plants grown for their seeds.
TZizania texana Hitchc., (of Texas), TEXAS WILD RICE. Perennial completely immersed and
long-streaming in flowing water or the upper parts emergent; culms usually 1–2(–5) m long;
ligules 4–12(–15) mm long, those of the upper leaves acuminate or caudate; leaf blades to ca. 1 m
long and to 13(–25) mm wide; inflorescence 16–31 cm long, to 10 cm wide, with staminate
spikelets on the spreading or ascending lower branches and pistillate spikelets on the appressed
or ascending upper branches; staminate spikelets 6.5–11 mm long, the lemma awnless;
pistillate spikelets when mature 9–12.5 mm long (excluding awns), the lemma awned. Clear
flowing water from springs of constant cool temperature (TOES 1993); Hays Co. (BRIT, TAES),
upper 4 km of the San Marcos River, within the city of San Marcos (Horne & Kahn 1997; Terrell
et al. 1997) near w margin of East TX; endemic to Hays Co., TX. Fall–spring, usually early
spring. While geographically much closer to Z. aquatica (SOUTHERN WILD RICE), which occurs
as far sw as LA (and potentially in e part of East TX), a phylogenetic analysis of molecular data
(Horne & Kahn 1997) indicated that Z. texana is more closely related to Z. palustris, (NORTHERN
WILD RICE). Horne and Kahn (1997) concluded that Z. texana is a relict of the last glacial period.
They suggested that as the post-glacial climate of TX became warmer and more arid, the increasingly
isolated populations of drought-sensitive WILD RICE were gradually eliminated as
spring systems dried up. The result is that at present Z. texana survives in only a single refugium
of cool spring water along the Balcones fault zone. This species exhibits low levels of
genetic diversity (Horne & Kahn 1997). The seeds are edible. This rare species has long been
endangered due to human modification of its habitat (Emery 1967, 1977), and it is officially
listed as a federally endangered species (Terrell et al. 1997; Terrell ined.). The most serious threat
to its survival is cessation of spring flow from the San Marcos Springs, which are fed by the
Edwards aquifer, the primary source of water for San Antonio and numerous other cities,
ranches, etc. (Poole 2002). (TOES 1993: I; RARE 2002a: G1S1LEE) � E
ZIZANIOPSIS Döll & Asch. CUT GRASS, MARSH-MILLET
AA wet area C3 genus of 5 species of tropical and warm areas of the Americas; 1 species occurs
in the se U.S. and Mexico and the other 4 in South America (Tucker 1988; Terrell ined.). Molecular
evidence suggests that within the Oryzeae, Luziola and Zizaniopsis appear most closely allied,
with Zizania relatively closely related. Leersia and Oryza, which appear to be each other’s
closest relatives, are in a second monophyletic lineage within the Oryzeae (Ge et al. 2002). The
common name CUT GRASS comes from the scabrous leaf margins, which can easily cut human
skin; they are sometimes described as “razor-sharp” (Steyermark 1963). (Named from Zizania,
and Greek: opsis, sight or appearance, from resemblance to the genus Zizania) (subfamily
Ehrhartoideae, tribe Oryzeae)
REFERENCES: Terrell & Robinson 1974; Tucker 1988; Holmes & Stalling 1990; Duvall et al. 1993a;
Brandenburg 2003; Terrell ined.
Zizaniopsis miliacea (Michx.) Döll & Asch., (pertaining to millet, Milum), GIANT CUT GRASS,
WATER-MILLET, SOUTHERN WILD RICE, MARSH-MILLET. Coarse, largely glabrous, rhizomatous,