Seed plants which fruit once only in the normal lifetime, and then die down to make way for the new set, are described as monocarpic. The habit is of much interest to students of ecology and succession. As ordinarily used, monocarpy is a rather fixed term which requires some extension, or even redefinition. In a stricter sense, the field of rye is monocarpic; though the usage is far less definite in its common application to plants much longer lived than annuals or biennials. There would, however, be a double reason for not calling a bracken fern monocarpic; since after the fertile frond bears its spores, the root-stock grows on, propagation being only secondarily dependent on either the sexual or the asexual generation. And somewhat similarly, any seed which, after the wilting down of a fertile stalk of one or more seasons, renews its growth from the root, is falsely monocarpic. It is an inadvertence on the part of botanists to cite the century plant as truly monocarpic, or any which does not fixedly persist by reseeding, or solely so persist. There appear to be some basic physiologic distinctions or phases in mnonocarpy. The Agave (or Yucca filamentosca, which regularly sends up the new buds, with very little germination of seed) does store the materials for the fertile shoot. But in such plants the length of the vegetative phase mnay be variable, or doubtless even local and individual. Besides, wherever the basal buds grow forward, there is some analogy to the fertile axis of limited growth in trees. The production of fowers or fruits usually means the growth of peduncular tracheidal or other structures old in the history of the plant, supplying greatly modified or reduced sporophylls; so that fruit maturity may mean, not merely exhaustion of the parent stem, but a heavy scar or injury to the stem not easily survived. Thus as a is modified from age to age, and the gap between fruit and vegetative structures widens, proliferation of the fertile axis may become difficult or quite impossible. And such has in fact become the condition in the vast majority of seed plants with renewed growth from the base of flower or cone. Particularly in the conifers the occasional appearance of proliferate cones may be regarded as reminiscent of a time when there were some normally proliferate types in the ancestral series. Contrariwise, the budding power of stems divested of their foliage or 2I8