Oecology of plants : an introduction to the study of plant-communities / by Eug. Warming, assisted by Martin Vahl. Prepared for publication in English by Percy Groom and Isaac Bayley Balfour.

  • Warming, Eugenius, 1841-1924.
Date:
1909
Catalogue details

Licence: Public Domain Mark

Credit: Oecology of plants : an introduction to the study of plant-communities / by Eug. Warming, assisted by Martin Vahl. Prepared for publication in English by Percy Groom and Isaac Bayley Balfour. Source: Wellcome Collection.

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    5. Size of the plant is of some moment, not only because in the struggle for existence the taller plants are enabled to establish a supremacy more easily, but also because they are more exposed to inclemency of climate ; shrubs reach greater altitudes and latitudes than trees, while dwarf- shrubs and herbs extend even farther than shrubs. 6. Duration of the leaves varies ; some live for only a few months, others for years. In all climates deciduous (summer-green, rain-green) and evergreen plants are met with side by side. This distinction is associated with edaphic conditions, and can be utilized in the classifica¬ tion of sub-divisions. 7. The adaptation of the assimilatory shoot to the conditions of tran¬ spiration, is determined by the substratum, and by the climate. Some plants assimilate mainly by their leaves, which exhibit very great variety in shape and structure ; but others depute their assimilatory function to the stem, and reduce their leaves. The shapes of leaves (their vena¬ tion, division, and so forth) depend partly upon systematic affinity, and partly upon the surrounding medium and climate ; they are probably of but slight value as a basis of oecological classification. 8. The capacity for social life is of great importance in the struggle between species, and consequently in the composition and physiognomy of the plant-community. This capacity is due in some cases to the prolific production of seed, but usually to more vigorous vegetative multiplication by means of travelling shoots, or shoots given off from the root. And this latter is to some extent determined by the soil (moist or wet soil, loose sandy soil, and so forth). In accordance with these considerations polycarpic plants may be grouped under four sub-classes :— (a) Renascent (Redivivus) herbs. (b) Rosette-plants. (c) Creeping plants. (d) Plants with erect long-lived shoots.1 We will now proceed to discuss these sub-classes, and, as a final step in the process of sub-division, we shall be able to define types that can be named after definite species or genera, e.g. Primula-type, Bromelia- type, Cycas-type, and so forth. (a) Renascent herbs. Polycarpic herbs whose assimilating and flowering shoots develop at a definite climatic time. The plant there¬ fore passes through a resting period, during which its hypogeous or epigeous renewal-shoots are protected by scale-leaves. When the favourable season arrives, the plant once more reveals itself (and is thus renascent). The photophilous shoots are aestival-annual and usually have long internodes and mesophilous leaf-structure. The perennating hypogeous parts are necessarily provided with reserve food. A great variety of types is included amongst these herbs. Some are ‘ spot-bound ’ [stationary, sedentary]; others are travelling plants. Among them are the following :— 1 This classification approximates to that proposed by Krause (1891). For the further sub-division of these sub-classes, and for the distinction of the various types included among these fundamental forms, we must refer to the characters mentioned in the paragraphs numbered 4-8.