The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

awnless barnyard grass, jungle rice, jungle ricegrass, or jungle-rice, small barnyard grass, watergrass

Habit Plants annual; erect or decumbent, cespitose or spreading, rooting from the lower cauline nodes. Plants annual or perennial; synoecious, monoecious, or dioecious; primarily herbaceous, habit varied.
Culms

10-70 cm;

lower nodes glabrous or hispid, hairs appressed;

upper nodes glabrous.

annual, usually solid, sometimes somewhat woody, sometimes decumbent, often branched above the base.

Sheaths

glabrous;

ligules absent, ligule region frequently brown-purple;

blades 8-22 cm long, 3-6(10) mm wide, mostly glabrous, sometimes hispid, hairs papillose-based on or near the margins.

Leaves

distichous;

sheaths usually open;

auricles usually absent;

abaxial ligules usually absent, occasionally present as a line of hairs;

adaxial ligules membranous, sometimes also ciliate, or of hairs, sometimes absent;

blades sometimes pseudopetiolate;

mesophyll radiate or non-radiate;

adaxial palisade layer absent;

fusoid cells usually absent;

arm cells usually absent;

kranz anatomy absent or present;

midribs usually simple, rarely complex;

adaxial bulliform cells present;

stomata with triangular or dome-shaped subsidiary cells;

bicellular microhairs usually present, with a long, narrow distal cell;

papillae absent or present.

Panicles

2-12 cm, erect, rachises glabrous or sparsely hispid;

primary branches 5-10, 0.7-2(4) cm, erect to ascending, spikelike, somewhat distant, without secondary branches, axes glabrous or sparsely hispid, hairs 1.5-2.5 mm, papillose-based.

Inflorescences

ebracteate (Paniceae) or bracteate (most Andropogoneae) panicles, racemes, spikes, or complex arrangements of rames (in the Andropogoneae), usually bisexual, sometimes unisexual;

disarticulation usually below the glumes, frequently in the secondary and higher order axes of the inflorescences.

Spikelets

2-3 mm, disarticulating at maturity, pubescent to hispid, hairs usually not papillose-based, tips acute to cuspidate.

bisexual or unisexual, frequently paired or in triplets, the members of each unit usually with pedicels of different lengths or 1 spikelet sessile.

Glumes

usually 2, equal or unequal, shorter or longer than the adjacent florets, sometimes exceeding the distal florets;

florets 2(-4), usually dorsally compressed, sometimes terete or laterally compressed;

lower florets sterile or staminate, frequently reduced to a lemma;

upper florets usually bisexual;

lemmas hyaline to coriaceous, lacking uncinate hairs, often terminally awned;

awns single;

paleas of bisexual florets well-developed, reduced, or absent;

lodicules usually 2, sometimes absent, cuneate, free, fleshy, usually glabrous;

anthers 1-3;

ovaries usually glabrous;

haustorial synergids absent;

style branches 2, free and close or fused at the base.

Caryopses

1.2-1.6 mm, whitish;

embryos 63-83% as long as the caryopses.

hila usually punctate;

endosperm hard, without lipid;

starch grains simple;

embryos large in relation to the caryopses, usually waisted;

epiblasts usually absent;

scutellar cleft present;

mesocotyl internode elongated;

embryonic leaf margins usually overlapping, rarely just meeting, x = 5, (7), 9, 10, (12), (14).

Lower

glumes about 1/2 as long as the spikelets;

upper glumes about as long as the spikelets;

lower florets usually sterile, occasionally staminate;

lower lemmas unawned, similar to the upper glumes;

lower paleas subequal to the lemmas;

upper lemmas 2.6-2.9 mm, not or scarcely exceeding the upper glumes, elliptic, coriaceous portion rounded distally, passing abruptly into a sharply differentiated, membranous, soon-withering tip;

anthers 0.7-0.8 mm.

2n

= 54.

Echinochloa colona

Poaceae subfam. panicoideae

Distribution
from FNA
AL; AR; AZ; CA; FL; GA; IL; KS; KY; LA; MA; MD; MO; MS; MT; NC; NJ; NM; OK; OR; PA; SC; TN; TX; VA; VT; WA; HI; PR; Virgin Islands
[WildflowerSearch map]
[BONAP county map]
Discussion

Echinochloa colona is widespread in tropical and subtropical regions. It is adventive and weedy in North America, growing in low-lying, damp to wet, disturbed areas, including rice fields. The unbranched, rather widely-spaced panicle branches make this one of the easier species of Echinochloa to recognize.

Hitchcock (1913) considered that 'colonum' was a non-declining contraction, but dictionaries of Linnaeus' time treated it as a declining adjective. Because Linnaeus was the first to name the species (as "Panicum colonum"), it seems best to follow the practice considered correct in his day; hence "E. colona".

(Discussion copyrighted by Flora of North America; reprinted with permission.)

The subfamily Panicoideae is most abundant in tropical and subtropical regions, particularly mesic portions of such regions, but several species grow in temperate regions of the world. Within the Flora region, the Panicoideae are represented by 59 genera and 364 species. They are most abundant in the eastern United States (Barkworth and Capels 2000). Photosynthesis may be either C3 or C4. All three pathways are found in the subfamily, but the PCK and NAD-ME variants appear to have evolved only once, while the NADP-ME pathways seems to have evolved several different times (Giussani et al. 2001).

The Panicoideae were first recognized as a distinct unit by Brown (1814), earlier than any of the other subfamilial taxa of the Poaceae. Its early recognition is undoubtedly attributable to its distinctive spikelets. Recognition of the tribe Gynerieae is recent (Sanchez-Ken and Clark 2001) and its placement in the Panicoideae, rather than the Centothecoideae, should be regarded as tentative.

Spikelets with two florets are found in many other subfamilies, but rarely do they follow the pattern of the lower floret being sterile or staminate and the upper floret bisexual. Development of unisexual florets within the Panicoideae appears to be consistent across the subfamily (LeRoux and Kellogg 1999), but differs from that in the Ehrhartoideae (Zaitcheck et al. 2000).

The Paniceae and Andropogoneae have their conventional interpretation in this Flora, so far as the North American taxa are concerned. Molecular studies, however, while strongly supporting the monophyly of the Andropogoneae, show the Paniceae to be paraphyletic, with two distinct clades. In one of these clades, most taxa have a chromosome base number of x = 9, but some have x = 10, and the taxa are pan-tropical in origin. The taxa in the other clade, with one exception, have a chromosome base number of x = 10 and are American in origin. This latter clade is sister to the Andropogoneae, which also have a chromosome base number of x = 10 (Gomez-Martinez and Culham 2000; Giussanni et al. 2001; Barber et al. 2002).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Blades of leaves on the lower 1/2 of the culms disarticulating from the sheaths; plants 2-15 m tall, unisexual, without axillary inflorescences; blades with midribs 5-15 mm wide
Gynerieae
1. Blades of most or all cauline leaves remaining attached to the sheaths; plants 0.05-6 m tall, usually bisexual, sometimes with unisexual inflorescences, often with axillary inflorescences; blades with midribs 0.2-5 mm wide.
→ 2
2. Glumes usually conspicuously unequal; lower glumes usually greatly exceeded by the upper florets; upper glumes from subequal to longer than the distal florets; lemmas of the upper florets usually coriaceous to indurate; disarticulation usually beneath the glumes, not in the axes of the inflorescence branches
Paniceae
2. Glumes usually subequal, usually exceeding and concealing the florets; lemmas of the upper florets hyaline to membranous; disarticulation frequently in the axes of the inflorescence branches
Andropogoneae
Source FNA vol. 25, p. 398. FNA vol. 25, p. 351. Author: Grass Phylogeny Working Group;.
Parent taxa Poaceae > subfam. Panicoideae > tribe Paniceae > Echinochloa Poaceae
Sibling taxa
E. crus-galli, E. crus-pavonis, E. esculenta, E. frumentacea, E. muricata, E. oplismenoides, E. oryzicola, E. oryzoides, E. paludigena, E. polystachya, E. pyramidalis, E. walteri
Subordinate taxa
Andropogoneae, Gynerieae, Paniceae
Synonyms E. colonum
Name authority (L.) Link Link
Web links