4. The genus rhynia is named after the locality
rhynia in aberdeenshire district of scotland
and possesses.
Two species, R gwynne vaughani and
R.major , R.major is larger than the former.
The genus was discovered in 1917 by
kidston and lang from Rhynia chert bed of
middle devonian.
continue….
5. The two species R.major,about 40-50 cms in
hight and R.gwynne-vaughani,about 20 cms
in height.
The plant grew in swampy marshes.it was
differentiated into horizontally creeping
rhizome and an upright branched shoot
without leaves.thre were no roots.
The upright branches were dichotomously
branched and gradually tapering,the
sporangia terminated these branches.
6.
7. They are club-shaped or cylindrical structures
borne terminally on the fine aerial branches[4
mm long and 1.4 mm broad].
Their wall is three layered: an outer epidermal
layer, a middle three cell rows thick layer and
an inner layer.
The outer layer is heavily cutinized.
The sporangium contained large number of
spores arranged in tetrads like the modern
ferns.
They are homosporous and measured 40 H in
diameter.
10. • Astroxylon is a genus of terrestrial
vascular plant which flourished in the
early devonian period.
• This plant branching stems that reached
12 mm in diameter and 40 cm in length.
• There aerial stems arose from a leaf-less
rhizome which bore smaller-diameter,
• Positively geotropic root-like branches.
• The rhizomes reached a depth of up to
20 cm below the surface.
