Arthragrostis Lazarides,. Nuytsia 5: 285
(1985).
Derivation:.
From Greek arthron (joint) and agrostis (grass), alluding to the
disarticulation of the panicle into component parts.
Taxonomic
revisions, nomenclatural references:. M.Lazarides, Nuytsia 5:
285–287 (1985); B.K.Simon, Austrobaileya 2: 238–239 (1986) and Austrobaileya
3: 585–587 (1992).
Key references
(keys and floras):. R.D.Webster, Australian Paniceae 12–13 (1987);
B.K.Simon, Key to Australian Grasses 73 (1993); D.Sharp and B.K.Simon, AusGrass
(2002).
W.D.Clayton &
S.A.Renvoize, Genera Graminum (1986), genus (484).
Native, endemic. 4 species,
from tropical Queensland.
Habit. Annual,
tufted to decumbent. Leaf blades narrow. Ligule a fringed membrane.
Inflorescence.
Inflorescence paniculate, an open panicle with branches ending in single
spikelets, open (7–10 cm long), not a compound pseudo-inflorescence.
Spikelet-bearing axes falling entire (the primary inflorescence branches
deciduous).
Spikelets.
Spikelets dorsally compressed, 2 flowered, with 1 fertile floret, solitary,
pedicelled. Fertile spikelets with lower incomplete floret(s), lanceolate,
falling with glumes, with a distinctly elongated rachilla internode between
glumes and with distinctly elongated rachilla internodes between florets. Upper
floret borne on a swollen stipe. Stipe beneath upper floret filiform (not
appendaged), homogeneous.
Glumes. Glumes
unequal or more or less equal, (the upper) long relative to adjacent lemmas,
hairless, pointed (upper glume acuminate) or blunt (lower glume acute to
rounded), awnless, non-keeled, dissimilar. Lower glume relatively smooth, 7
nerved. Upper glume scabrid, 11 nerved.
Florets. Lower
incomplete floret(s) sterile. Lemmas awnless, 9–11 nerved, considerably longer
than the upper lemmas, less firm than fertile lemmas (membranous), not becoming
indurated. Fertile florets 1. Lemmas acute, decidedly firmer than glumes,
smooth, white in fruit, entire at apex, pointed to blunt, muticous, with a
clear germination flap, obscurely nerved, glabrous, having margins tucked into
palea. Palea relatively long, entire, cartilaginous, like the lemma. Lodicules
2. Stamens 3.
Kranz Anatomy.
C4.
Habitat.
Mesophytic. In scrub. Species of open habitats.
Classification.
Panicoideae; Paniceae.
Notes. A genus
with uncertain affinities within the Paniceae. Its mode of disarticulation
suggests a close relationship with the bristle-bearing genera, from which it is
distinguished by the stipitate upper floret. Close relatives may include Yakirra,
Whiteochloa and some Panicum species. (Webster 1987).
Types Species. A.
deschampsioides (Domin) Lazarides.
Biogeographic
Element. Clifford & Simon 1981, Simon & Jacobs 1990: Endemic.
