A morphological study of some members of the genus Pallavicinia . female plants, x 2. The base of the aerial shoot, or frond, like the rhizome of which it isthe continuation, is quite destitute of the wing-like lamina found in theexpanded portion of the frond. The cylindrical stalk, as it ascends, be-comes gradually flattened dorsi-ventrally and develops a narrow wingon either side which widens until it forms the beginning of the expanded,fan-shaped lamina of the frond. The first dichotomy occurs when theyoung frond is 3-4 cm. in height. The forking is repeated from two tofour times, and there
A morphological study of some members of the genus Pallavicinia . female plants, x 2. The base of the aerial shoot, or frond, like the rhizome of which it isthe continuation, is quite destitute of the wing-like lamina found in theexpanded portion of the frond. The cylindrical stalk, as it ascends, be-comes gradually flattened dorsi-ventrally and develops a narrow wingon either side which widens until it forms the beginning of the expanded,fan-shaped lamina of the frond. The first dichotomy occurs when theyoung frond is 3-4 cm. in height. The forking is repeated from two tofour times, and there thus results the palmately divided leaf-like shoot, theslender central strands of the delicate segments simulating almost exactlythe venation of a true leaf. In the archegonial plants these fan-shaped 12 GENUS PALLAVICINIA fronds are about cm. in width (Fig. 5). In the male plants they aresomewhat smaller. The apex of each segment is indented, and the mar-gin is wavy, with conspicuous teeth, or narrow lobes, which are usuallypointed and hooked (Fig. 4, A).. A. Median section of an archegonial receptacle; B. A nearly mature archegonium. C. D. Ventral part of two old archegonia. E. Receptacle containing an embryo; cal. calyptra F. Transverse section of a similar receptacle. G. H. Archegonial receptacles. Pallavicinia Zollingeri. in, involucre ; per, perianth. METHODS 13 The male plant (Fig. 1, A) is smaller and more delicate than thefemale, while the lamina is more strongly corrugated. The antheridiaoccur in thick patches upon the dorsal surface of the midrib of the ulti-mate segments of the frond, and each antheridium is subtended by a scalewhose margins may be either entire or toothed (Fig. 4, A, B). Morethan one crop of antheridia may be formed on a frond, and one some-times finds old patches of scales with the remains of discharged antheridiaon the older portion of the frond whose terminal segments bear youngerantheridia. Fig. 4, D shows a cross-section of a segment of t
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
