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39 
V. False oat-grass. 
Avena elatior L. or Arrhenatherum elatius Mertens & Koch. 
A. Portion of a plant, shewing the contracted panicle. 
B. Portion of a panicle in flower; the panicle is spreading. 
1. Spikelet before flowering, side-view. 
2. Spikelet in flower, side-view; to the right is the lower male flower with the awn, to the 
left the upper hermaphrodite flower. 
3. The hermaphrodite flower with the lower pale removed, shewing two lodicules, 3 stamens, 
the pistil and the upper pale with its keels. 
,, 4. Pistil of the hermaphrodite flower, shewing the ovary and the feathery stigmas. 
» 9. Rudimentary pistil of the male flower. 
» 6. The false fruit: to the left is the upper fertile flower containing the caryopsis, to the 
right the barren male flower with the awn. 
7. The same, with the empty pales removed, side-view. 
, 8. The same ventral surface, shewing the stalk. 
9, The caryopsis, dorsal surface, shewing the embryo. 
, 10. The caryopsis, side-view. 
, 11. Diagram of the spikelet; the fertile flower below, the barren above. 
12. Transverse section of a leaf-blade (after Lund), shewing the low flat ribs. 
13. The obtuse ligule; the dots on its outer surface represent the hair. 
1} 
Botanical description. False oat-grass forms loose tufts of grass. The extravaginal branches 
lengthen out somewhat beneath the ground, and form, so to speak, short stolons; this gives the loose 
character to the grass. The culms. 2 to 4& ft. high, are smooth, shining, and erect, or, at times, 
somewhat ascending at the base. The J/eaf-sheath is glabrous; the ligule, short, obtuse, and hairy on 
the outer surface (fig. 13); the blade, narrow and rough, with low flat ribs (fig. 12), and convolute in 
the bud. The inflorescence is a panicle, contracted before flowering (fig. A), but afterwards widely sprea- 
ding (fig. B). The spikelets are numerous, and of a whitish-green colour, often tinged with violet and 
brown. The spikelet contains two flowers: — the lower male and awned, the upper hermaphrodite and 
usually awnless (figs. 2 and 441). The glwmes are two: — the upper, longer than the other, and three- 
ribbed; the lower, narrower and one-ribbed (figs. 1, 2 and 11), Each flower has two pales. The lower 
pale of the male flower is furnished with a long awn, which is bent and twisted, and arises near the 
base of the pale (figs. 1, 2 and 6). The lower flower has 3 stamens, and a rudimentary pistil (fig. 5) 
on which the stigmas are not represented; it is, therefore, barren or male. The upper flower has 3 
stamens, and a pistil with feathery stigmas (figs. 3 and 4), i. e. it is hermaphrodite and fertile. Both 
flowers have lodicules (figs. 3 and 41). The axis of the spikelet is prolonged beyond the base of the 
upper flower, forming the stalk (fig. 8). Flowering goes on as in Perennial rye-grass (which see), At 
maturity, the contents of the spikelets detach, and the glumes are left empty behind. The two ripe 
flowers of the spikelet, together with their pales, remain united, and form the false fruit: it is com- 
posed of a pair of empty pales from the lower flower, and a pair of pales containing a caryopsis derived 
from the upper flower (fig. 6). When the empty pales are removed (fig. 7), the fruit stands on a short 
hairy stalk, which is prolonged along the inner face of the upper pale (fig. 8). The caryopsis (figs. 9 
and 10) is fusiform, and acute at the apex and base; the ventral surface has no furrow; at the base 
of the dorsal surface lies the embryo; the apex has a few short hairs. 
A variety of this is the common weed known as bulbous-rooted oat-grass (Arrhenatherum elatius 
var. bulbosum, Koch.) This variety occurs mainly on moist sands and loams, and, in such localities, is 
Explanation 
of plate. 
Botanical 
description. 
Varieties. 
