. Practical botany. Botany. 266 PEACTICAL BOTANY. LTVERAVORTS 248. Riccia. Among the bryophytes the liverworts are sun- pier than the mosses, and some of the liverworts are extremely simple. Upon moist soil at the margins of ponds and streams and sometimes free-floating in quiet water, the small, green, disk-like Riccia or Bicciocarpus plants may be seen (Fig. 222). Upon careful observation, root-lil^e projections (rhizoids) may be observed upon the lower surface. The plant is two-lobed, with a depression or notch between the lobes. This body is frequently spoken of as a thallus, though it is
. Practical botany. Botany. 266 PEACTICAL BOTANY. LTVERAVORTS 248. Riccia. Among the bryophytes the liverworts are sun- pier than the mosses, and some of the liverworts are extremely simple. Upon moist soil at the margins of ponds and streams and sometimes free-floating in quiet water, the small, green, disk-like Riccia or Bicciocarpus plants may be seen (Fig. 222). Upon careful observation, root-lil^e projections (rhizoids) may be observed upon the lower surface. The plant is two-lobed, with a depression or notch between the lobes. This body is frequently spoken of as a thallus, though it is not like the thallophyte body. The rhizoids extend downward and backward from the notch. The upper surface of Riccia is greener than the lower surface. Near its margin the plant may be but one or a few layers of cells in thickness. Evidently Riccia, though a prostrate plant, is much more complex than any of the algse. It is more complex in that it has distinct upper and lower surfaces, with root-like hairs grow- ing from the lower surface. It is also to be noted that it has a distmct apical or growing end and a basal end. Chlorophyll is borne in the compact body cells, and livmg as the plant does, upon damp earth or in water, it can readily secure the materials from which foods are manufactured. It is more complex than the protonema of moss, but less so than the leafy shoot. In reproducing itself each individual plant of Riccia forms within its tissues both kinds of reproductive organs. One of these is an archegonium, the tip of which just reaches the upper surface of the plant. In the swollen part of the arche- gonium is the large egg cell, which is therefore deeply em- bedded in the plant tissues. The antheridia also open to the Asimpleliver- wort (Bicciocarpus) It has distinct, upper and lower surfaces, bears rlii- zoids (r) on the under surface, and branches from a midrib into leaf- like structures il). About five times natural size. Please note that these images a
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