Floret development, embryology, and systematic position ofOryzopsis hendersoni(Gramineae)

摘要

Previous research has shown thatOryzopsis hendersonishares two features withStipaand one withOryzopsis. A study of floret development and embryology was undertaken to obtain more points for comparison. Most of the 26 features ofO. hendersoniresulting from this study are characteristic ofStipaand notOryzopsis. Therefore, it is proposed thatO. hendersonibe transferred toStipa.Evidence from this and other studies demonstrates that the ovules of grasses and of certain other angiosperms are stem-borne; that the development of grass lodicules can be leaf-like, stem-like, or intermediate; and that the grass carpel develops as a single, continuous, leaf-like structure. This developmental evidence disproves the generally accepted notions that all angiosperm ovules are carpel-borne, that all grass lodicules are leaf-like, and that the grasses have three carpels. Since these notions have resulted from the acceptance of completely speculative phylogenies, it is proposed that such misleading phylogenies be rejected and avoided in the future.It is also recommended that, because the word homology means different things to different people, the word homology be replaced by clear and common, but equally concise, terminology.