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2021-2022 Academic Year
Meiktila University
Department Of Botany
First Year MSc
Botany Specialization
First Semester
Module Name Evolutionary Survey of
Plant Kingdom
Module No. Bot. 611
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Practical No. (6)
Origins and Traits of Vascular Plants
Early vascular had branched sporophytes, but they were not dependent on
gametophytes for nutrition.
These ancient vascular plants were less than 20 cm tall, their branches to
become more complex and to have multiple sporangia.
Their bodies become increasingly complex, competition for space and
sunlight probably increased.
That competition may have stimulated still more evolution in vascular plants,
eventually leading to the formation of the first forests.
The main traits that characterize living vascular plants are:
-life cycles with dominant sporophytes,
-transport in vascular tissues, and
-well-developed roots and leaves, including spore-bearing leaves called
sporophlls.
Earlier, mosses and other bryophytes have life cycles dominated by
gametophytes.
Fossils suggest that a change began to develop in the ancestors of vascular
plants, whose gametophytes and sporophytes were about equal in size.
Further reductions in gametophyte size occurred among extant vascular
plants.
Thus, the sporophyte generation is the larger and more complex form in the
alternation of generation.
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