ISSN:
1615-6110
Keywords:
Angiosperms
;
Podostemaceae
;
Tristichoideae
;
Indotristicha ramosissima
;
Rheophytes
;
water plants
;
life history
;
development
;
root-shoot model
;
leaf-stem intermediates
;
phyllotaxis
;
flower structure
;
systematics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The developmental morphology ofIndotristicha ramosissima, a submerged rheophyte from South India, is described. Besides creeping organs (called roots) there are branched shoots with two kinds of short-lived photosynthetic appendages: scales and compound structures (called ramuli). These ramuli may be interpreted as leaf-stem intermediates because they combine typical leaf characters (extra-axillary position, determinate growth, subtending an axillary bud) and typical stem characters (nearly radial symmetry, acropetal development with apical meristem, arrangement of the scaly subunits helical or irregular). Floral shoots arise from axillary exogenous buds along the vegetative shoots, occasionally also from endogenous buds along the roots and vegetative shoots. The uppermost scales and ramuli of each floral shoot form a cup-like structure around the base of the terminal flower.Indotristicha is thought to be primitive within theTristichoideae (Podostemaceae). Some morphogenetic switches are postulated in order to deriveIndotristicha from a putative ancestor that still showed the classical root-shoot model typical of most angiosperms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00937964
