抽象的

Pentoxylales A Remarkable Order in the Evolution of the Plants

Teena Agarwal*

Gymnosperms are the plants of the great biodiversity, they have the tremendous evolution in the past, a whole palaeobotany in the Mesozoic era is the sign of the development of this great ecosystem in the past. Fossil pteridospermales, bennettitales and the cordaitales and pentoxylales are the examples of the fascinating fossil history of the plants. In this review articles we are presenting some of the aspects of the fossil order entitled as the pentoxylales. This fossil group was discovered from the several places of the world, some of the places were in India like the Mesozoic hills of Rajamaha lhills, however complete fossil ecosystem has not been reported in these places of the India as intact but the fossil coverage was incomplete, they were probably shrubs and the trees, they have the long and the short shoots, the short shoots have the male and the female sporangia with the sporangiophores on the tipsl, eaves were spirally arranged and they were polystelic, wood rays were uniseriates, leaves were found think and the lanceoloate and the venation was in the form of the open form instead of the closed network. Females organ were liked the stalked mulberries and the male organ were in the form of the sporangia with the pollen inside the cavity of the sporangia. The male sporangia were fused in the disc with the several kinds of sporangiophores on the disc. This fossil group has several kinds of the linkage with the other fossil groups and some of the peculiar feature which makes the order unique in the palaeobotanical world.