Several rhizomes of Dennstaedtiaceae were examined anatomically. Extra-axillary buds were pointed out as to Microlepia platyphylla (Fig. I-3), which is presumably an isolated species with a single closely related species, M. kurzii, derived from the primitive stock of Microlepia. Branching pattern of the rhizomes is uniform in Microlepia (dichotomous branching, commonly with no extra-axillary buds), but very variable in Dennstaedtia, one of which (Fig. II-2) is homologous to that of Hypolepis punctata (Fig. II-8), and the other (Fig. II-9) is also homologous to that of Leptolepia novae-zelandiae (Fig. II-10). Petiolar branching of Hypolepis ontogenetically agrees with that of Leptolepia (compare Fig. III-3 to Fig. II-10). The dichotomous branching of rhizomes, for example shown in Microlepia, is presumably derived from the Leptolepia-type branching by the process 10→9→5→6→7 (Fig. II) with some leaves change to bear no buds.
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