Plant Morphology and Anatomy in the Tropics-The Need for Integrated Approaches

Abstract

Plant morphology, like justice, must not only be done, it must be seen to be done. It must be done because it is foundational to many major disciplinessystematics, ecology, and plant physiology. Similarly plant morphology is initially an observational discipline; the pun is intentional because I want to speak from the point of view of the research worker who needs direct access to his material and the opportunity to see the functional significance of form and structure which is investigated. Modern high speed travel has made easy the traditional process of what may be called body-snatching, i.e., the initial collection of fluid-preserved or dried materials which the plant morphologist uses for much of his work. Body-snatching has contributed the largest part to our understanding of tropical plants and needs to be actively encouraged because it provides the initial comparative background to any biological enquiry. Here I want to emphasize the need for elaboration of or departure from this classical approach in what I will call integrated studies of biological features of tropical plants. Integration here has a dual meaning, it refers to the need to combine elements of disparate disciplinesanatomy, physiology, biochemistry, ecology, and plant-animal interactions-but also emphasizes an approach which recognizes the organism itself as an integrated entity so that something of its total biology is revealed. Corypha provides a simple but dramatic example of a tropical plant consisting of a single hapaxanthic module in which the switch from vegetative to sexual growth is complete, with marked contrast between the massive unbranched vegetative axis to the highly branched determinate inflorescence, with resulting proliferation of another generation of meristems. Here vegetative and reproductive phases are sharply segregated, but they must occur in the right sequence and at the right time. A striking example, which illustrates the way in which a branched organism can function as an integrated physiological unit is provided by Cerberiopsis candelabrum (Apocynaceae), a small tree in New Caledonia which is monocarpic (Veillon, 1971). Here a tree that is architecturally precisely branched in the initial vegetative stage eventually shows synchronous flowering and fruiting which ends in itsdeath-rather like many annual weeds. A second species, C. comptonii, a treelet with smaller leaves, is not monocarpic. This genus therefore provides material for the study of a biological problem which may be approached comparatively but requires access to field populations. The plants under consideration are large and can only be represented in herbaria by fragments. An appreciation of the adaptive significance of this life style would draw on several disciplines-anatomy, physiology, and reproductive biology. It has to be appreciated that modern travel in the tropics is easy and a