22 PROCEEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 
under t.3418: 1940) has pointed out that the Aveneae may be divided 
into two groups distinguished partly on the nature of the awn. In the 
typical group ( Aveneae subtribe Euaveneae Beck) the awn is dorsal 
and its column often subterete, or at least not flattened or laterally 
winged. The column is formed by the continuation of the middle nerve 
and not by the splitting of the lemma into three segments. On the 
other hand, in the second group ( Aveneae subtribe Danthomeae Beck), 
the lemmas are usually two-lobed, and the awn when present arises in 
the sinus of the lobe. Here the column of the awn is flattened and its 
formation is due to the gradual splitting of the apex of the lemma 
into three segments. 
Eriachne and Pheidochloa differ from each of these groups, for in 
these genera the awn is a continuation of the fusion of all the nerves 
of the unlobed lemma, and perhaps they are as well placed in the 
Festuceae. 
The name Pheidochloa is derived from </>eiSos“, sparing, thrifty; 
and yAoa grass. It refers to the scanty inflorescence, 2-flowered 
spikelets, the two minute anthers and the very fine and thin lodieules. 
Both collections are from similar types of country — ill-drained 
sandy land supporting an open dwarf -tree community of Melaleuca spp. 
associated with chiefly small annual grasses and Cyperaceae belonging 
to the genera Eriachne, Ectrosia, Heterachne, Schdzach yri u m, 
Thaumastochloa and Fimbristylis. 
EXPLANATION OF PLATES. 
Plate I. — Aristida wtilis F.M.Bail. drawn from Blake 8149; figs. 2-12 from 
same specimen. 
Fig. 1, plant, natural size; 2, 3, spikelets, X 3, tlie former with “normal 77 
glum.es and well-developed lateral awns, the latter with ‘‘inverse 77 glumes and the 
lateral awns absent; 4-8, details of spikelet, X 6: — 4, 5, glume tips from two 
spikelets, a, upper, and h, lower; 6, lemma, front view; 7, palea; 8, flower with 
lodieules separated; 9-12, top of column with base of awn, from four spikelets, 
showing variation in development of lateral awns, X 15. 
Plate II. — Pheidochloa gracilis S. T. Blake, gen. nov., sp. nov., drawn from 
Blake 13732 (type). 
Fig. 1, plant, natural size’ 2, ligule with top of leaf-sheath partly flattened and 
base of blade; 3, spikelet; 4, lower glume; 5, upper glume; 6, florets, side view, 
greater part of awns removed; 7, 8, floret from front and back respectively; 
9, lemma, expanded, from the back; 10, palea from in front; 11, flower with the 
lodieules separated; 12, 13, grain from back and front respectively; 14, transverse 
section of grain; 15, diagram of spikelet. — Fig. 3X3; figs. 2, 4-14 X 8. 
