/ 



Some new anatomical cha,racters for certain Oramineae, 



Theo. I^olm. 



(With two figures in the text.) 



Some imporlant new facts to be brought out in this study 

 require the brief Statement ot a few fundamentals of plant-ana- 

 tomy and especiallj the matter of the structure of what has been 

 called the parenchyma-sheath. — This sheath, which consists of 

 a Single layer of relatively short eells, surrounds the mestome- 

 bundles of the leaves and, partly also, of the stem of the mayo- 

 rity of monocotyledonous plants : Gramineae, Cyperaceae, Junca- 

 ceae etc., and has also been found in nearly all the Orders of the 

 Dicotyledones. It is generally thin-walled and contains Chlorophyll 

 to the same extent as the surrounding mesophyll or it may appear 

 as totally destitute of Chlorophyll, and with some of the cells 

 thick-walled, especially on the leptome-side, when in contact with 

 supporting bundles of stereome. Such Variation in the relative 

 thickness of the cell-walls and in the cell-content may be seen in 

 the same leaf by comparing mestome-bundles of different size 

 and development. But one character is constant, namely, that 

 the parenchyma-sheath borders directly on the mesophyll or on 

 the cortical parenchyma, whether this is differentiated into pali- 

 sades or not, thus connecting the leptome and hadrome with the 

 assimilating tissue. 



The literature of this subject, the structure of the parenchyma- 

 sheath, is extensive and well known. But besides the ordinary 

 parenchyma-sheath, as we may call it, some others oecur inside 

 this, namely, the mestome-sheath, deseribed bySchwendener*; 

 as characteristic of all the Cyperaceae and a number of Gramineae 

 and Juncaceae, and finally the inner chlorophyll-bearing sheath 

 which H a b e r 1 a n d t **) detected in certain species of Cyperus. 

 Of these the mestome-sheath is generally prominently thick-walled 



*)Schwendener, S., Die Mestomscheiden der GroTwiwcew- Blätter. 

 (Sitzungsber. d. K. Academie, Berlin. 1;<90. p. 405.) 



**) Haberlandt, G., Physiologische Pflanzenanatomie. Leipzig 1884. 

 p. 174. Fig. 61. 



Bd. XI. Beiheft 2. Bot. CeutralbL 1901. 7 



