114 POA RIGIDA. 
ribbed, the marginal ribs being broad, and having a white 
line down the centre; intermediate ribs indistinct, dorsal rib 
dentate on the upper portion. Inner palea somewhat shorter, 
and having two green marginal ribs. Length from three to 
five inches. Root annual, fibrous, and woolly. 
- Flowers in the middle of July, and ripens its seed in a 
month. 
Poa rigida is unlike all others except P. loliacea; however 
P. rigida has the apex of upper glume on a level with the 
base of the third floret, whilst in P. loliacea it is on a level 
with the base of the fourth floret. 
The specimen illustrated was gathered on Colwick Park Wall, | 
by Mr. Joseph Sidebotham. 
