17 



Las uo exodermal expansions, tliougli its cells are less regular than 

 those of tbe male plant. Bands of colorless parenchyma exteud in one 

 row of cells from the bulliform cells to the opposite face of the leaf and 

 are never interrupted below by hypodermal fiber. Fiber is present at 

 the margin of the leaf and there are a few fiber-cells, often only one or 

 two, above and below each bundle. The cells are thick-walled with 

 scarcely distinguishable cavities. The large bundles are like those of 

 Distichlis spieata. They differ from those of the male plant in having 

 not only a band of sheath cells dividing the xylem from the phloem, but 

 also almost invariably a band of several rows of the same cells divid- 

 ing the phloem into two j)arts. Also there is a sheath of one row of 

 cells that are thick- walled around the sieve portion of the bundle, but 

 thin walled above the xylem. 



ERAGROSTIS OBTUSIFLORA. 



In this grass the leaves are more slender and less rigid than those 

 of Jouvea pilosa, but sections from ditierent parts of a leaf show the 

 same variations of general form, the basal section being curved and the 

 median y-shaped (figs. 3 and 4, PI. VIII). The apical section differs from 

 the median in degree only and not in form. The presence of ridges and 

 furrows on the upper tace, the shape of the bundles, and the general 

 character of the bands of hypodermal fiber (fig. 7, PI. IX) are like those 

 of Jouvea pilosaj as is also the concentric arrangement of the tissues, 

 and the bands of colorless parenchyma between the bundles. The lower 

 surface of the leaf is slightly furrowed. Long pilose hairs and two- 

 celled hairs are altogether wanting or are rare on the upper surface, but 

 otherwise the exodermal exi)ansions are as in J. pilosa. The epidermis 

 of the lower face differs in that the cells covering colorless parenchyma 

 are very irregular in form and in the thickness of the walls. These 

 cells frequently have curved beak-like expansions that project over the 

 stomata ; their walls are very unevenly thickened and show many radial 

 canals. They are frequently interrupted b}" glandular bodies that have 

 a spherical hyi)odermal portion, a narrow neck, and -a capitate exoder- 

 mal portion. Similar glands occur in the superior ei^idermis on the 

 sides of the ridges. The epidermal cells are all very small in trans- 

 verse section. In a basal section primary and secondary bundles occur 

 in regular alternation, but in a median section two or three secondary 

 ones intervene between two j^rimary. The primaiy bundles differ slightly 

 from those of a corresponding section of J. pilosa in that a row of thick- 

 ened cells separates xylem from phloem. The secondary bundles differ 

 in the marked line between xylem and phloem and also in the nature of 

 the sheath. This consists of a single row of cells. Below and above the 

 bundle these have relatively smaller cavities and thicker walls than the 

 corresponding cells of J. pilosa, but frequently on either side of the 

 bundle there occurs one cell much larger than the others, of more angular 

 shape, and in almost any section taken at random a transverse, pitted 

 14837— Xo. 8 2 



