156 KANSAS ACADEMY OF SCIENCE. 



The color of the rhizoids varies from a light brown to a dark purple, the 

 brown being most common. In the cellular structure of all three forms the 

 cells are separated by oblique septa. 



In the Snhagnaceae very few small rhizoids are to be found. There is a 

 very close relationship between rhizoids and protonema threads, as each may 

 develop into the other. The rhizoids are hyaline when first formed, but as 

 they enter the soil they become brownish and contain oil drops and consider- 

 able protoplasm. 



The buds of the protonema develop into the stem or leaf-bearing axis. 

 In the simpler mosses, there is no differentiation in the stem tissue, except 

 that three or four layers of cells are closer and firmer, with an inner axis of 

 fundamental tissue, having larger, thinner-walled cells, as Gymnostomum 

 glaucum, Hedwigia ciliata, and Hylacomium splendens. In others, more 

 highly developed, there is besides, also, an axial bundle of very thin-walled 

 and very narrow cells, and a central bundle or cylinder, as in Grimmia, Pu- 

 naria, Bartramia, Mnium, Bryum, and many others. The cell walls of the 

 central bundle are thickened perceptibly only in Polytrichum, Atrichum, and 

 Dawsonia. Thus we have all the gradations, from scarcely a suggestion of 

 a vascular system to signs of medullary rays in the most highly developed 

 mosses, which is similar to that of some of the lowest vascular plants. (See 

 "Sach's Botany," p. 365, and "Goeble's Special Morphology," p. 167). 



The form of the stem ranges from very short and simple (less than one 

 millimeter in length), as in Phascum and Buxbaumia, to large branched 

 plants, from three to five decimeters long, as in various Hypnum, Poly- 

 trichum, Sphagnum, and others. 



The diameter of the stem varies from one-tenth millimeter to one milli- 

 meter, and is always firm and elastic. 



The manner of branching is very characteristic, as it may be dendroid or 

 tree-like, simply or compoundly pinnate, fastigiately or irregularly branched, 

 and either erect or creeping. Again the branching may be complanate or 

 flattened so that the branches and leaves are all' in one plane (in this case 

 being usually creeping), or the plants may be pulvinate or closely compact 

 and cushion-like, or simply a tangled mat. In a few cases the plants occur 

 singly, as in Funaria and others. 



The color of the stem may be either brownish, yellowish, or more often 

 green and chlorophyllose; and the surface may be either rotigh and scaly or 

 smooth and shining. The plants are either annual, as in Phascum and others, 

 or perennial, as in Sphagnum, Polytrichtim, etc. 



Mosses bearing fruit on the apex of the stem belong to the Acrocarpi, 

 while those bearing tiieir fruit laterally belong to the Pleurocarpi. The 

 acrocarpous mosses send out a branch each year, at the apex, just beneath 

 the base of the seta, producing a continuation of the stem called an inno- 

 vation. The pleurocarpous mosses send out true branches, and have sym- 

 metric stems. 



The leaves of mosses are always simple, sessile, and arranged in two 

 or more rows, according to the position of the successive segments. If they 

 are arranged in two rows and flattened, they are said to be complanate, as 

 in Fissidens (see plate IV), or they may be in three rows, as in Fontinalis; 

 but in most mosses the leaves are arranged in spirals. The phyllotaxy varies 

 from two-fifths to three-eighths, as in Sphagnum, Andreaea, and Polytrichum. 

 ■ The leaves may be erect or spreading, turned back, reflexed, curved like 

 a scythe, or falcate, and again turned to one side or secund. 



The leaves in some species are large and broad (one-half centimeter 



