. Botany for high schools and colleges. Botany. OHARACEJE. 333 plant is composed of a jointed stem, which bears whorls of leaves at regular intervals. The stem is one-celled in trans- verse section, as in Nitella, or it has a large axial cell, which is surrounded by many long narrow ones, which form a cortical envelope, as in many species of Oliara. In some species the stem and leaves become incrusted with lime, giv- ing to them a good deal of hardness and brittleness. {a) The class is readily divisible into two orders — Nitelleae and Charese.* Order Nitellese.—In this order the stem and leave
. Botany for high schools and colleges. Botany. OHARACEJE. 333 plant is composed of a jointed stem, which bears whorls of leaves at regular intervals. The stem is one-celled in trans- verse section, as in Nitella, or it has a large axial cell, which is surrounded by many long narrow ones, which form a cortical envelope, as in many species of Oliara. In some species the stem and leaves become incrusted with lime, giv- ing to them a good deal of hardness and brittleness. {a) The class is readily divisible into two orders — Nitelleae and Charese.* Order Nitellese.—In this order the stem and leaves are always naked—, not cor- ticated ; the leaves are in whorls of five to eight, and bear large leaflets, which are often many - celled. The sporocarps arise sin- gly or in clusters in the forkings of the leaves, and each has a crown consisting of two superimposed whorls of five cells each. These delicate plants occur in ponds and streams, and are rarely more than a few centi- metres in ^^^S^^- a, an isolated shield, m, seen Two genera—Nitella from within, witii manu •riiim bearing Tlie filaments, &, in A m„i„.n.,nn «ro wliicli the spevraatozoids nre developed ; c, a small portion ana i oiypeua — aie ^^ ^^^^ ^^ ^^^ filaments, th • fpermatozoids not shown ; A, diatino-uished by the two free spermatozoids. a and 6 X 50; o and A X 800.— •i-" iii *!.„ After Thuret. position of the anthe- ridium, which is terminal upon the single node of the primary leaf in the former, while in the latter it is lateral, and the primary leaf has two or three nodes. The species of Nitella (ten to fifteen of which are American) are ar- * What follows is mainly from a synopsis of the Characese, furnished for this work by Dr. T. F. Allen, tlie author of " Characese Americanae," now issuing in numbers. Use has also been made of Dr. B. D. Hal- sled's paper on the " Caasification and Description of the American species of Cljarace
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1885
