126 Botanisches Ceutralblatt. — Beiheit 2. 



covered by one or two subepidermal Inyers of thick-Avalled stereome, 

 ■\vhich in transversc section forms a long, linear group above and 

 beloAv the ribs, besides that stereome also occurs in the furrows 

 of the dorsal face of the blade. But the structure of the two is 

 identical as to the palisades, the parenchyma- and the mestome- 

 sheaths. 



Of these three Chlorideae, Schedonnardus shows a large midrib 

 supported by a large mass of stereome. A very different structure 

 is, however, exhibited by Chloris petraea Sw, from sandy sea- 

 shores, which has been described and figured by Du val- Jouve 

 and Kearney (1. c.) and which possesses a large colorless tissue 

 underneath the entire ventral epidermis, which is here differentiated 

 into a broad band of bulliform cells above the strongly carinate 

 midrib. A single parenchyma- and a mestome-sheath was also 

 observed in this genus, besides that the mesophyll consists of pali- 

 sades, arranged radially around the mestome bundles. But the 

 leaf of Chloris 'petraea is sniooth, without furrows, and is scabrons 

 only on the lower face. 



Glyceria airoides Thurb. (Festucaceae). 



Besides being very abundant in alkaline soil on the plains of 

 Colorado, this species may also ascend the mountains to an ele- 

 vation of 10,300 ft., where it occurs on dry, rocky slopes. It is, 

 thus, one of the Gramineae, characteristic of the plains, and as 

 will be shown in the following pages, it exhibits a leaf-structure, 

 which is so very much unlike that of other species of Glijccriay 

 hitherto examined by various authors. The leaf is very uarrow, 

 detply furrowed on the upper face and covered Avith quite long, 

 unicellular, pointed hairs on both faces of the blade. Small bulli- 

 form cells are present in the furrows, but none are developed 

 above the midrib ; the cell-walls of epidermis are much thickened 

 on both faces of the blade, and the stomata, level with the epi- 

 dermis, are located in that part of epidermis, which covers the 

 mesophyll, but are most frequent along the sides of the furrows. 

 The stereome is not very thick-walled, and accompanies the 

 mestome- bundles as large groups on the leptome-side, bordering 

 on the parenchyma- sheath but as only a few layers or a few cells 

 on the hadrome-side of these, separated by layers of mesophyll. 

 The palisade-tissue is not as typically developed as in other 

 Gramineae from the same localities, and the cells are usually 

 relatively short, except those that border directly on the paren- 

 chyma-sheath. These are a littlc longer and are arranged radially 

 around the nerves. No lacnnes were observed in the mesophyll, 

 and Ave mention this, bccause these are very conspicuous in leaves 

 of other species of Gli/ceria. The larger mestome-bundlcs are 

 oval, and the smaller orbicular in transverse section ; they are 

 located in the ribs, and the mediane of these is not more promi- 

 nent than the others. They are all surrounded by a small-celled, 

 thin-walled parenchyma-sheath, Avhich contains Chlorophyll, and 

 which is completely closed in all tiie bundles. There is also a 



