A monopodial rosette model of shoot formation as a program of secondary-aquatic grasses appearing

Abstract

On the basis of comparative morphological analysis of the structure of life forms the concept “key biomorph” is offered; it is a mien of a plant which reflects adaptation to the conditions of a definite habitat (a static aspect, a model) and a definite stage in evolutional changes of biomorphs (a dynamical / evolutional aspect). The paper shows a comparative morphological range of key biomorphs in accordance with a monopodial rosette model of shoot formation per gradient of moisture increase in the direction: a floodplain meadow – shores, shore fronts – the water line – a water body. Polygonum bistorta is considered the original key biomorph, changes in it could occur in three lines: 1) Polygonum bistorta – Butomus umbellatus – Nuphar lutea; 2) Polygonum bistorta – Scirpus lacustris – Eleocharis palustris; 3) Polygonum bistorta – Limosella aquatica – Stratiotes aloides. It seems that appearing of secondary-aquatic grasses with a monopodial rosette model of shoot formation was provided by the following modes of morphological evolution: deviation on the shoot level; abbreviation of the bud stage in shoot formation, in forming a part of the shoot (inflorescence), in the anatomic structure of the shoot and the ontogenesis of the original plant; prolongation of the bud phase in shoot development and ontogenesis of the genet.