MR. C. B. CLARKE ON PANICUM SUPERVACUUM. 407 
On PANICUM SUPERVACPUM, sp. nova. 
~ By C. B. Crak&r, F.L.S. 
[Read 1st December, 1887.] 
Panicum supervacuum (i. e. redundant) differs from all other 
Panicums (and their allies) by having constantly an extra flower 
interposed between the male and female flowers in each spikelet. 
In the annexed figure, representing one spikelet dissected out, 
A is the lower glume, B the upper glume, C the lower flower 
(always reduced to an empty lower pale in the present species so 
far as seen), D the redundant flower, E the perfect closed flower, 
which is hardened brown, showing, under a low magnification, 
obscure transverse wavy marks, as is common in Panicum. The 
hardening of the fertile flower in Panicum is caused by a cor- 
rugated thickening of the walls of the cells. Asis so common 
in Panicums of the P. prostratum group, the glumes A, B, and 
the lower flower C are pilose, while the fertile flower E is 
glabrous. 
The intermediate flower D is intermediate in character between 
the male C and the fertile E. Sometimes it has an upper pale 
anda small rudiment (possibly of a pistil); and in these cases it 
is partially hardened, quite glabrous, and shows the corrugated 
thickened cells and very obscure transverse wavy marks, as in 
the lower pale of the fertile flower. 
Sometimes it is empty, and then less 
thickened, and occasionally minutely 
Pilose. The interposed flower is in- 
serted in regular alternation; so that 
the fertile flower E comes over the 
lower glume A, instead of over B as 
in all other Panicums. The pedicel 
18 articulated below the lower glume; 
and the species shows so far no ten- 
dency towards Isachne: it is a very 
Common-looking Panicum, near P. 
Prostratum, Lam., and P. antidotale, 
tz., and, without dissection, might 
be actually sorted into the Kew bundle 
of P. prostratum, which comprises & 
considerable range of forms. 
On my showing this species to Prof. 
Oliver, he called my attention to the cases of P. rude, Nees, and 
LINN. JOURN.— BOTANY, VOL. XXIV. 2x 
