. Botany for high schools and colleges. Botany. Fig. 239.—Plant of An- thoe&ros kevis. K, on the right, sporogonia un- opened ; K, on tlie left, Fporoffonia opened.—After Prantl. takes place simply by the decay of the sporogonium; in Anthoceros the long sporogonium splits vertically into two long valves (Pig. 339), while in the greater part of the class it splits regularly into a definite number (four to six) of recurv- ing segments; in the latter the elaters, which are present, doubtless aid in setting the spores free. The struc- ture and development of the elaters are shown in Fig. 240.
. Botany for high schools and colleges. Botany. Fig. 239.—Plant of An- thoe&ros kevis. K, on the right, sporogonia un- opened ; K, on tlie left, Fporoffonia opened.—After Prantl. takes place simply by the decay of the sporogonium; in Anthoceros the long sporogonium splits vertically into two long valves (Pig. 339), while in the greater part of the class it splits regularly into a definite number (four to six) of recurv- ing segments; in the latter the elaters, which are present, doubtless aid in setting the spores free. The struc- ture and development of the elaters are shown in Fig. 240. The following are tlie principal orders of the Hepaticse: Order Ricciacese.—Consisting of terrestrial or aquatic annual plants of small size ; the plant- body is a dichotomously branched thalloid stem, which beard a row of scale-like leaves upon the under side. The sexual organs occur singly on the upper side of the stem, and the sessile, spherical sporogonia (capsules) are immersed in it or sessile upon it; the capsule breaks irregularly upon the decay of its walls ; and there are neither perianth nor elaters. Order Antliocerotese. — Terrestrial annual plants with an irregularly branched thallus. The sexual organs are inihedded in the upper surface of the f loiid, and are of very simple structure ; the sporogonia are long and narrow, and dehisce by splitting into two valves ; perianth none ; and the elaters, when present, imperfect and rudimentary. Order Marchantiacese. — Terrestrial perennial plants, with a thick, creeping, and dichotomously branched stem, furnished beneath with numerous scale-like leaves and root-hairs ; above, the stem is provided with a well-developed epidermis, and pe- culiar stomata of a complex structure, communi- ii°^ii)'|"broken°awaT eating with lozenge-shaped cavities (Figs. 78 and A., A, are matiirft 79, pp. 91-3). The sexual organs are developed on ^^°;^ Le^MlmitaS special erect branches, and they may occur on the Decaisne. same,
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1888
