イセハナビ属とその近縁属にみられる有刺花粉の由来について [in Japanese] Observation on the echinulate pollens of Strobilanthes s.l. and its allies [in Japanese]
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Discussion has been made as to the origin of the echinulate pollen found in Strobilanthes s.l. and its allies. The pollens of Strobilanthes s.l. and its allies usually have longitudinal bands. The banded pollens can generally be classified into two types by the sculptures of the bands : 1) the pollens with foveate bands (type 1 in table 1 ; fig. 1-A) and 2) those with the bands with scalariform reliefs (type 2 in table 1 ; fig. 1-B, J, K). The pollens with tuberculate bands (type 5 in table 1 ; fig. 1-C, D) are sometimes found in the species groups which usually have the pollens with foveate bands or those with scalariform bands, and seem to derive easily from both types of the pollens. The echinulate pollens (type 6 in table 1) usually are globose and have spines or spinules evenly distributed on the surfaces (fig. 1-I). Transitional forms (fig. 1-E, F, G, H) are found, however, between this type of echinulate pollen and the pollens with tuberculate bands. The presence of these transitional forms suggests the possibility that the echinulate pollens have derived through the pollens with tuberculate bands from the pollens with foveate bands or those with scalariform bands. The spinules of the echinulate pollen of Lamiacanthus occur on indistinct ridges which draw a characteristic pattern on the pollen surface (fig. 1-O). The pollens with similar pattern of ridges are rarely found in the species referable to group V in BREMEKAMP's system (fig. 1-N). A series of transitional forms found in the species referable to group V (type 3 & 4 in table 1 ; fig. 1-K, L, M) indicates that the pattern of the ridges in question has derived as the result of the rearrangement of the parallel ridges which have derived from the scalariform reliefs through the suppression of the transverse ridges (cf. fig. 2). The echinulate pollen of Lamiacanthus seems to have derived as the result of the development of spinules on the pattern of the ridges thus derived.