NITELLA, AG.* 



Revised Synopsis. 



A. MONARTHRODACTYL/E, (ultimate segments of the leaves, 



one-celled, 

 a. FURCATE, leaves once divided. 



a. HOMCEOPHYLL^;, verticils composed of similar leaves. 

 * GYMNOCARP/E, organs of fructification not enveloped 



in jelly. 

 DIOIC.E. 



f APICULAT/K, leaves abruptly pointed, or some- 

 times (in No. 2) obtuse, coronula, evanescent. 



1. Membrane of the spore smooth. 



N. opaca, Ag. 



2. Membrane of the spore granulated. 



N. obtusa, Allen. 



f f ACUMINATE, leaves gradually tapering to a sharp 

 point, coronula persistent. 

 + Plants small, 



3. Oospores aggregated, N. Montana, Allen. 



4. Oospores, isolated, N. Blankinshipii, Allen. 

 -f- + Plants large, habit of N. subglomerata. 



5. N. Missouriensis, Allen. 



f APICULATA, coronulae evanescent. 



6. N. flexilis, Ag. 

 f f ACUMINATE:, coronulae persistent. 



^General variations, common to many species of Nitella. Variations in the 

 internodal cells of the principal slem give rise to elongated and compact forms. 

 In the latter the distance between verticils becomes so small that the fruiting 

 verricils are condensed into " heads," as in N. glomerulifera. when less compact, 

 but still dense, forms called " nidifica " conglomerate! or " compete ta '' are found. 

 It is noticed in general that, when portions of the plant fruit freely, the stem is 

 not so well developed and frequently the leaves become shorter. Sterile plants 

 are apt to be more diffuse in their habit. In some cases, as in the new JV. obtusa, 

 the internodal cells are elongated, but the leaves of the verticils, especially the 

 fertile ones, are quite abbreviated. In such cases the form may be called " con- 

 globata.'^ Again, the segments of the leaves may be disproportionately elongated 

 or contracted. All these and other variations are to be expected in the same 

 species, and must not be taken as specific distinctions but as simple variations or 

 forms. The markings on the membrane of the oospore are most important in 

 distinguishing between species and varieties, since, as shown by Dr. Nordstedt, 

 they are constant for each species. They may be known as Nordstedt's markinsg. 



