Question

hlo guys....


here is your question.....

write the morphology, Anatomy and affinities of Rhynia​

Answer 1

External Structure of Rhynia:

The plants of Rhynia were herbaceous. R. major was 50 cm. in height and 1.5 to 6 mm in diameter whereas R. gwynne-vaughani was only about 20 cm. in height and 1 to 3 mm in diameter.

The plant body was differentiated into a subterranean rhizome with an abruptly turned upright photosynthetic aerial shoots. Roots were absent but at places rhizome was provided with tufts of unicellular rhizoids (Fig. 1 A, B). The aerial shoots were cylindrical and leafless with a tapering dichotomously branched system.

In R. major the aerial shoots were smooth but in case of R. gwynne-vaughani many adventitious branches were present on the aerial shoots as well as rhizome. These branches perhaps help in vegetative propagation.

Internal Structure of Rhynia:

Transverse section (T.S.) of Aerial shoot and Rhizome:

Anatomically, the aerial shoots and rhizome are almost similar. T. S. of aerial shoot can be differentiated into three parts: epidermis, cortex and stele (Fig. 2 A).

(a) Epidermis:

It was the outer-most surrounding layer. It was one cell thick and covered by thin cuticle. In aerial shoots it was interrupted at certain places by stomata but stomata (Fig. 2 B) were absent in rhizome.

(b) Cortex:

Epidermis was followed by cortex. It is differentiated into outer cortex and inner cortex. The outer cortex was only 1-4 cells thick, thin walled and without intercellular spaces. The inner cortex had large intercellular spaces and its cells had chloroplast. It is thought that this was the chief photosynthetic region of the plant. The endodermis and pericycle layers were absent.

Internal Structure