Holm, Some v.ew anatomical characters for certain Gramineae. 127 



mestomesheath of cells with the inner wall very thick and porou& 

 in most of the bundles. 



Glyceria airoides has then tlie same principal leaf-structure 

 as other genera inhabiting the dry plains : namely the deep furrows^ 

 the hairy covering, the dense mesophyll of palisades around the 

 mestome-bundles and the relatively narrow leaf-blade. 



Duval-Jouve (1. c.) has described and figured leaves of 

 Glyceria aquatica, ftuitans and nervata, in which wide lacunes 

 traverse the blade between the nerves ; and the mestome-bundles 

 de not form any projecting ribs in these species, except the 

 mediane one, which is located in the keel. The leaf of G. jiui- 

 tans is, however, deeply furrowed on its upper face, but the 

 mestome-bundles are, nevertheless, to be found in the bottom of 

 the furrows, while the ridges are merely occupied by a few layers 

 of mesophyll, surrounding lacunes of very great breadth. This 

 same author has also described G. feshicaeformis, which to some 

 extent is more like our G. airoides, as to its leaf, which is quite 

 thick and narrow, besides that the mesophyll is compact without 

 any lacunes. It differs, however, from that of G. airoides by it& 

 smooth surface and by the large colorless tissue, that covers the 

 hadrome of the larger mestome-bundles, as well as in that no hairs 

 are developed. 



Distichiis spicata (L.) Greene (Festuceae). 



This grass, originally described by Linnaeus as Uniola spi- 

 cata, and later by Rafinesque as Distichiis ^naritima, inhabits salt- 

 marshes along the Atlantic and Pacific coasts of this country and 

 is also very frequent in the interior on low alkaline plains. Our 

 material was collected near Denver in Colorado. 



The structure of the leaf resembles strikingly that of Cala- 

 movilfa, but no hairs are developed, while short papillae abound 

 on both leaf-faces : on the ridges of the upper, and in the shallow 

 furrows of the lower. The blade is very deeply furowed above, 

 and the furrows are occupied by large and well-developed bulli- 

 form cells. Epidermis is everywhere very thick - walled, but 

 especially outside the stereome on the lower face. Stomata are 

 present on the sides of the furrows and are almost level with the 

 epidermis, but surrounded by thick, curved papillae. A colorless 

 tissue of about two rows of cells in four layers is located under- 

 neath the bulliform cells, in the broad Spaces between the ribs, 



The stereome is thick- walled, but occurs only in small gioups 

 above and below the mestome-bundles, but there is no large group, 

 supporting the midrib, and the margins have only a very small 

 group of this tissue. The mesophyll is dense and consists princip- 

 ally of a single layer of palisades, arranged radially around the 

 mestome-bundles. These have the usual parenchyma- and mestome- 

 sheath, of which the former is large-celled, a little thick-walled 

 and contains Chlorophyll. The latter is strongly thickened and 

 is only continuous in the largest mestome-bundles. Many of the 

 companion-cells have also very thick walls; thus the leptome pre- 



