Morphological studies in the Gramineae

Summary

The present paper deals with the vascular anatomy of the spike and spikelets of twenty species of Andropogoneae. The vascular anatomy of the spikelet indicates that there has been an abbreviation of the axes in the spikelet. In the majority of the Andropogoneae where the lower floret is reduced to its lemma, the bundles, of the second palea arise conjointly with the lateral bundle of the two lemmas and the second empty glume. In those members where the lower floret is also present the bundles of both the paleae, the lateral bundles of the two lemmas and in some cases those of the glumes arise in the form of a single vascular mass on either side.

Attention has been drawn to the various trends of specialization in the spike and spikelets of this tribe. There is a marked tendency for the imperfection of the pedicelled spikelet which may be variously reduced and in some cases is entirely unrepresented. There is yet another tendency towards the elaboration of the outer empty glumes and the suppression of the lemma I and the palea II which tend to be hyaline and non-vascular and in some cases are completely wanting.

Occasional increase in the number of lodicules has been recorded forMnesithea laevis andHeteropogon contortus.