Nature and development of plants . Fig. 196. One of simpler thal-loid Jungermani-ales, Pallazicinia,showing the rhi-zoidal growth onthe under surfaceof the thallus anda mature sporo-phyte arising froma cup-like perianthwhich is surround-ed at its base withinvolucrate leaves.—H. O. Hanson. 262 STRUCTURE OF LEAFY HEPATICS hepatics and probably stand nearer the ancestral type than anyother form. The Marchantiales represent a line in which thetissues of the thallus have attained a considerable degree of. Fig. 197. One of the leafy Jungermaniales, Porclla: A, branch of theplant bearing several spor
Nature and development of plants . Fig. 196. One of simpler thal-loid Jungermani-ales, Pallazicinia,showing the rhi-zoidal growth onthe under surfaceof the thallus anda mature sporo-phyte arising froma cup-like perianthwhich is surround-ed at its base withinvolucrate leaves.—H. O. Hanson. 262 STRUCTURE OF LEAFY HEPATICS hepatics and probably stand nearer the ancestral type than anyother form. The Marchantiales represent a line in which thetissues of the thallus have attained a considerable degree of. Fig. 197. One of the leafy Jungermaniales, Porclla: A, branch of theplant bearing several sporophytes. B, under surface of a branch, showingthe lobing of the leaves and a row of minute scale-like leaves. C, portionof a branch bearing an archegonium surrounded by cup-like perianth withminute involucrate leaves at base. D, branch with cone-like antheridialbranchlets. At the left a single leaf is shown with globular antheridiumin its axis. E, section of a branch similar to C. The archegonium is seensurrounded by the perianth and below the involucrate leaves. The sporo-phyte is nearly mature and ready to elongate. It consists of a round cap-sule containing elaters and spore mother cells that are dividing to formfour spores each. Below the capsule is the stalk or seta which ends in afoot buried in the tissues of the branch. At the, right is an unfertilizedarchegonium that shows the original position and size of this organ.—II. (). I tanson. DEVELOPMENT OF PLANTS 263 differentiation, but
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