1905] HOLM--MUNROA SQUARROSA 131 
of our plants have been studied from this particular point of view, 
and the following notes on the histology of Munroa squarrosa may 
be regarded, therefore, as a small contribution towards the knowl- 
edge of this interesting plant association. With this object in view, 
the writer has examined the structure of the roots, the culm, the 
proper leaves, and the prophyllon, and finally the flowering glumes 
of both forms of spikelets. 
THE ROoTS.—The roots are thin, hairy, not very strong, rela- 
tively short, and but little ramified. In a mature root the epidermis 
and the moderately thick-walled hypoderm persist, but the cortex, 
Fic. 11.—Munroa squarrosa.—Transverse section of a mature root: e, endoder- 
mis; p, pericambium; /, leptome. X 360. Fic. 12.—Transverse section of a capil- 
lary lateral root: h, proto-hadrome; the other letters as above. X 560 
which consists of only three or four layers, collapses radially. The 
inner walls of the endodermis (jig. rz, e) are considerably thickened 
with distinct layers and pores; and it surrounds a pericambium 
which is thickened throughout. Therefore the location of the proto- 
hadrome vessels could not be clearly ascertained, and the inner por- 
tion of the central cylinder is occupied by a mass of thick-walled 
conjunctive tissue with about ten broad rays of hadrome. The lep- 
tome constitutes very small groups, when viewed in transverse sec- 
tions (fig. rz, 1). A younger stage of the root shows these same ele- 
ments much less thick-walled. Thus it was possible to distinguish the 
pericambium cells from the proto-hadrome vessels, and it was noticed 
that the latter had penetrated the pericambium in all places. If 
one of the capillary lateral roots (fig. r2) is examined the same struct- 
ure is observed, but the center of the root is here occupied by a large 
vessel, and the hadromatic rays are merely represented by four proto- 
hadrome vessels (fig. 12, h), all of which are located inside the peri- 
