Question

origin and evolution of angiosperms​

Answer 1

Answer:

Angiosperms evolved during the late Cretaceous Period, about 125-100 million years ago. ... Angiosperms did not evolve from gymnosperms, but instead evolved in parallel with the gymnosperms; however, it is unclear as to what type of plant actually gave rise to angiosperms.

Answer 2

Evolution of Angiosperm

Explanation:

1. A essential trouble that have to be handled is whether or not the angiosperms are monophyletic or polyphyletic because of inadequate fossil facts, the question of phyla of the angiosperms nonetheless remains unsolved. however, angiosperms are a natural organization and include characters, which cause them to unique from all other vascular flowers.

     (a) Monophyletic foundation: As a collection, the angiosperms have normally been viewed as being monophyletic. but, no exact fossil evidences are available in favour of the monophyletic beginning.  it is  totally at the fact that present-day angiosperms display amazing consistency in their characters, i.e. presence of sieve tubes in all, uniform staminal shape, characteristic endothedial layer of the anther wall, double fertilization, and formation of triploid endosperm, which can be considered defining capabilities of angiosperms and support the monophyletic grouping.The monophyletic beginning of angiosperms is supported via Hickey & Doyle on the basis of their studies of mono-sulcate pollen.

(b) Polyphyletic origin;several phylogenists inclusive of Cronquist, Hughes, games, Krassilov and Meeuse have argued that the angiosperms are polyphyletic i.e. dicots and monocots originated from special primitive stocks at distinct instances, and attained their gift reputation through parallel or convergent evolution. The principle of polyphylesis is also supported by using the fossil information of variety in perianth and the character of carpel in both dicots and monocots. The polyphyletic starting place of angiosperms is similarly supported by using the reality that primitive orders of both the monocots and dicots do not display any close dating in their characters,as a  fossil information endorse that angiosperms, as a set, are monophyletic, and their families or corporations of families are polyphyletic. however, recently, phylogenetic analyses the usage of nuclear, mitochondrial, and plastid gene sequences have aided in clarifying relationships among the numerous angiosperm families.