Rytidosperma semiannulare (Labill.) Connor
& Edgar. New Zealand J. Bot. 17: 332 (1979).
Classification. (GPWG 2001) : Subfamily Danthonioideae. Tribe
Replacement Name: Arundo
semiannularis Labill., Nov. Holl. Pl. 1: 26, t. 33 (1804).
Type of Basionym or
Protologue Information: T: Herb. Webb 114, (K).
Recent synonyms: Danthonia semiannularis, Notodanthonia
semiannularis (Labill.) Zotov.
(books and floras):  G.Bentham, Flora Australiensis 7 (595 as Danthonia
semiannularis),  C.A.Gardner, Flora of Western Australia 1 Gramineae
(57 as Danthonia semiannularis),  D.Sharp & B.K.Simon, AusGrass,
Grasses of Australia,  J.Jessop, G.R.M.Dashorst, F.M.James, Grasses
of South Australia (306),  S.W.L.Jacobs, R.D.B.Walley &
D.J.B.Wheeler, Grasses of New South Wales (308).
 J.Jessop, G.R.M.Dashorst, F.M.James, Grasses of South Australia (305, Fig. 239),  S.W.L.Jacobs,
R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th edn
Perennial. Culms erect, 20–45 cm tall, 3 -noded. Mid-culm nodes glabrous.
Leaf-sheaths glabrous on surface. Ligule a fringe of hairs, 0.5 mm long.
Leaf-blades straight, involute, 7–15 cm long, 1–2 mm wide. Leaf-blade surface
Inflorescence solid, a panicle. Panicle lanceolate, 5–8 cm long.
Spikelets pedicelled. Fertile spikelets many flowered, with at least 2 fertile
florets (5–6), comprising 5–6 fertile floret(s), with diminished florets at the
apex, cuneate, laterally compressed, 7–16 mm long.
similar, thinner than fertile lemma. Lower glume lanceolate, chartaceous, much
thinner on margins, without keels, 7 -nerved. Upper glume lanceolate, 7–11 mm
long, chartaceous, without keels, 5 -nerved.
Fertile lemma 1.8–5 mm long, without keel, 9 -nerved. Lemma surface indumented.
Lemma apex lobed, awned, 1 -awned. Median (principal) awn from a sinus, 6.5–11
mm long overall, with a twisted column. Column 2–3 mm long. Lateral lemma awns
absent. Lodicules present. Anthers 3. Grain 1.2–1.8 mm long.
Distribution: Australasia, Pacific, and North America.
Distribution: Western Australia, South Australia, New South Wales,
Drummond, Menzies. South Australia: Northern Lofty, Southern Lofty,
South-eastern. New South Wales: North Coast, Central Coast, South Coast,
Central-Western Slopes, South-Western Plains. Victoria: East Gippsland,
Gippsland Plain, Grampians, Midlands, Otway Plain, Otway Range, Wilsons
Promontory, Volcanic Plain, Wannon. Tasmania: King Island, Furneaux
Group, North West, North East, West Coast, Central Highlands, Midlands, East
Coast, South West.
Notes. There is
substantial variation in the length of the lemma lobe setae, and the relative
length of the awn column. Some of this variation appears to indicate a
north-south cline along the east coast, but some may also indicate a
relationship between R. longifolium and R. gracile. R.
semiannulare is closely related to R. gracile and R. longifolium
by the lemma back indumentum and the long paleas. R. gracile can be
distinguished by the long-villous leaf-sheaths, and extravaginal branching. The
distinction between R. longifolium and R. semiannulare is not that simple. Generally the species can
be separated by the growth-habit, with R. semiannulare having basal
leaves, while in R. longifolium they are cauline. In addition the leaves in R.
longifolium tend to be long, more
slender, and recurved, while in R. gracile they are broader and more straight. However,
it may be difficult to separate plants from Gippsland (e.g. Beauglehole
66818, Beauglehole 29961). There are also some collections from the
Blue Mountains (Carne NSW19670, Mair in NSW17811) which have the
setae of R. longifolium and the habit of R. semiannulare. There
are some collections which are intermediate to R. setaceum - these are
discussed under the latter species.
in south-eastern Australia, from Sydney to Adelaide, in clearings in
rain-forest, and generally in wet, often shady habitats; also in tall woodland.
Flowers Nov. to Jan.