Sentence Examples

  • It is, however, probable that a considerable group of true Ferns, allied to Marattiaceae, existed in Palaeozoic times, side by side with simpler forms. In one respect the fronds of many Palaeozoic Ferns and Pteridosperms were peculiar, namely, in the presence on their rachis, and at the base of their pinnae, of anomalous leaflets, often totally different in form and venation from the ordinary pinnules.
  • These curious appendages (Aphlebiae), at first regarded as parasitic growths, have been compared with the feathery outgrowths which occur on the rachis in the Cyatheaceous genus Hemitelia, and with the 'anomalous pinnules found in certain species of Gleichenia, at the points of bifurcation of the frond.
  • The sporangia were large pyriform sacs, shortly stalked, and borne in tufts on the branches of the fertile rachis, which developed no lamina.
  • It is characteristic of Zygopteris and its near allies that two rows of pinnae were borne on each side of the rachis, at least in the fertile fronds.
  • On the fertile rachis the sporangia were borne in tufts, much as in the preceding genus; they were still larger, reaching 2.5 mm.

How would you define rachis? Add your definition here.

comments powered by Disqus