SEDGES, 101 
respects closely resembles Carex, a long bristle arises from 
under the ovary within the utricle, projecting considerably 
beyond it, and bearing a strong barb or reversed hook at the 
tip. This is evidently a contrivance for the distribution of 
the seed by means of passing animals, and it serves 1ts pur- 
pose most efficiently. 
Fig. 202, Spike of Uncinia, with Wig. 208. Utricle of Uncinia, 
é flowers above and ? flowers with barbed spine (mag.). 
below. 
27. GRASSES. 
The structure of a typical grass is perhaps most readily 
comprehended by the examination of the common Oat (Avena 
sativa). The external and most manifest characters have 
already been pointed out—vyiz., the hollow rounded culm, 
closed at the joints; the sheaths of the leaves split to the 
pase ; and the presence in most 
cases of a ligule at the junction 
of the blade and sheath. 
The flowers are collected 
into small spikelets, and these 
are arranged on slender pedicels 
im open panicles, the form of 
which varies considerably in 
different varieties of oats. Hach 
spikelet bears externally two 
scale-leaves or glumes, which 
are usually called the empty 
glumes. As arule two flowers 
are enclosed in these outer ° 
glumes, one large and fully de- 
veloped, the other smaller, and 
there is often in addition the ig. 204. Spikelet of Oat (mag.), 
rudiment of another flower eg), empty glumes; jg, Howenhe 
; : glume; a, awn; p, palea; st.ji, 
present. Hach flower is also sterile flower. mat S 
enclosed in two scale-leaves: 
the outer and larger one, which overlaps the imner by both 
lts edges, is called the flowering-glume, and it generally 
