1906] CURRENT LITERATURE “es 
Anatomy of Cyperaceae.—The comparative anatomy of the Cyperaceae has 
been studied by PLowMan,3" and as usual the chief interest centers in the 
stem. Amphivasal bundles are found throughout the rhizomes of all large-leaved 
species and at the nodes of aerial stems; elsewhere the bundles are collateral. 
The amphivasal bundles arise through the introduction into the node of the 
numerous leaf-trace bundles, and are independent of the branching of the stem. 
Hence the leaf is to be regarded as the dominant factor in the development of 
the stelar characteristics of the family and probably of the other monocoty- 
ledonous families. The course of the bundles in the rhizome approaches the 
“palm type,” but in the culm the leaf-trace bundles pass down as cortical bundles 
through one internode and then fuse with the bundles of the central cylinder 
by a ring-like amphivasal plexus. The seedling and in some cases the floral 
axis show a simple tubular stele, which is to be regarded as the primitive condi- 
tion, in contrast with the medullary and amphivasal bundles occurring in many 
parts of the plant. A cambium is present in the bundles at the nodes of Scirpus 
cyperinus and other species. These features indicate that the Cyperaceae 
is one of the more primitive groups of monocotyledons, though showing signs 
of specialization and reduction, accompanied by a high degree of anatomical 
unity. The view which derives the monocotyledons from an essentially dicoty- 
ledonous ancestry receives further support. The author proposes a division 
of the family into ‘‘Amphivasae’”’ and “‘Centrivasae;” he also gives a key to 
the genera, based on anatomical characters. The paper is accompanied by a 
number of excellent photomicrographs.—M. A. CHRYSLER. 
Origin of Cycadaceae.—WorspDELL3? has published a résumé of his views 
as to the origin of the Cycads from the Pteridosperms, with full bibliography. 
The part dealing with the origin of axial structures is of greatest interest; and the 
thesis is that the Medullosan ancestry is clear. It is claimed that the coty- 
ledonary node and the axis of the strobilus are the two principal regions for 
revealing ancestral characters. Much stress is laid upon Matrte’s discovery 
of polystely in the cotyledonary node of Encephalartos Barteri; and also upon 
the very irregular orientation of the bundles of the peduncle of Stangeria. 
According to the author’s view, the endarch cylinder of Lyginondedron and of 
the Cycads is of polystelic origin, coming from Medullosan ancestors, each 
constituent bundle being the homologue of the single bundle of the monostelic 
_ Heterangium. The endarch condition arises from the degeneration of the 
internal vascular tissues. Numerous illustrations are given, intended to show 
how the various vascular structures of both Pteridosperms and Cycads suggest 
this view and are most easily explained by it. The whole presentation is 
3* PLlowMaN, A, B., The comparative Se and phylogeny of the Cyper- 
_ aceae. Annals of Bota 20:1-33. pls. I-2. t 
32 WorDSELL, W. C., The structure and origin of the Cycadaceae. Annals of 
_ Botany 20:129-159. figs. 17. 1906. 
