. The Characeae of America. 26 When there are two upper and two lower nodal cells to each bract, and both sets develop into a cortex, the stem becomes " diplosiiche corticata," when, as in Ch. sejuncta and all the allied sub-species of Ch. gymnopus, there are eight nodal cells, three upper and three lower develop into cortex cells and the two lateral cells remain undeveloped. In this case the leaf is, like the stem, " iriplostiche ; In a number of species, especially in many Ameri- can species, the lowest in- ternode of the leaf remains naked, while the median in-
. The Characeae of America. 26 When there are two upper and two lower nodal cells to each bract, and both sets develop into a cortex, the stem becomes " diplosiiche corticata," when, as in Ch. sejuncta and all the allied sub-species of Ch. gymnopus, there are eight nodal cells, three upper and three lower develop into cortex cells and the two lateral cells remain undeveloped. In this case the leaf is, like the stem, " iriplostiche ; In a number of species, especially in many Ameri- can species, the lowest in- ternode of the leaf remains naked, while the median in- ternodes are corticated. This is the case in Ch. hy- dropitys and its allied spe- cies, in Ch. sejuncta and the sub-species of Ch. gym- nopus (see Fig. 30). In the first growth of a stem from the protonema, in the earliest shoots from perennial stems and in many abnormal growths, portions of the stem and leaves may be naked, in normally corticated spe- cies. F'S- s, BRANCHES.—From the basilar node of a leaf (stem node) there arise not only cortex cells and stipular cells, but also new shoots, which may be called branches ; these arise always in the axil of the first leaf of the verticil (or, in some Nitellae, two shoots arise from the first and second leaves). The leaf which develops a shoot in its axil develops no cortex system, and the neighboring cortex cells have to close in and fill the gap. So, on the leaf, when a sporangium arises (always in the axil of the first bract), no cortex system develops from that bract upward. Many species of Characese are perennial in the sense that new growths arise from nodes of old stems that have retained their vital- ity over winter. This is especially true of Ch. fragilis in the North and Ch. gymnopus Humboldtii in the South. In some cases the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfec
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