237 



that has gained wide acceptance though not adopted by Engler 

 and Gilg. 



The relation of gymnosperms to ferns was supported by the 

 discovery of cihated sperm-cells in Ginkgo, by Hirase, in 1895; 

 later similar discoveries were made in cycads. This relation was 

 confirmed by the finding of fossil seed-bearing ferns by Oliver 

 and Scott, in 1903. The ferns now connect so closely with the 

 higher plants that the old grouping Pteridophyta and Sperma- 

 tophyta is no longer justified. 



In 1900 Jeffrey proposed two main groups of vascular plants: 

 Lycopsida (club-mosses and horsetails) with continuous woody 

 cylinder and sporangia on the ventral surface of the sporophylls, 

 and Pteropsida (ferns, gymnosperms, and angiosperms), having 

 woody cylinder with foliar gaps and sporangia on the dorsal 

 surface of the sporophylls. Since the club mosses difTer more 

 from the horsetails than do the groups of the Pteropsida among 

 themselves, Scott proposes three groups: Lycopsida, Sphenopsida 

 (horsetails and sphenophylls) , and Pteropsida. C. E. Bessey 

 makes six groups of vascular plants, Lepidophyta, Calamophyta, 

 and Pteridophyta, Cycadophyta, Strobilophyta (conifers) and 

 Anthophyta (flowering plants). Following in part along lines 

 suggested by Hallier, Bessey considers the monocotyledons as 

 derived from dicotyledons, the latter forming two main lines: 

 buttercup series, with receptacle an axis; and rose series, with 

 receptacle more or less cup-shaped. Apetalous flowers are con- 

 sidered as reduced forms. 



\'an Tieghem has proposed a number of morphological systems 

 in which the structure of the ovule is emphasized. "We may 

 question, says Rendle in his "Classification of Flowering Plants," 

 whether in view of the ephemeral nature of such systems, an 

 author is justified in proposing so large a number of new terms." 



Evidence appears increasingly conclusive that monocotyledons 

 are derived from dicotyledons, and therefore should be placed 

 after these. This view was already suggested by Strasburger, 

 and has been developed by Miss Sargant, Hallier, and others. 

 The probable line of development appears to be Ranunculaceae 

 to Alismaceae. Another possible connection may be Piperaceae 



