CLASSIFICATION OF RHYNIA
Kingdom :- Plantae
Division :- Pteridophyta
Sub-division :- Psilophytopsida
Class :- Rhyniopsida
Order :- Rhyniales
Family :- Rhyniaceae
Genus :- Rhynia
EXTERNAL FEATURES OF RHYNIA
- Rhynia is a fossil member (not found living in the present age), discovered from Rhynichert Beds (or upper Devonian era) in Aberdeenshire of Scotland, by Kidston and Lang in 1917.
- The two species R. major, about 40-50 cms in height and R. gwynne-vaughani, about 20 cms in height, found at this station, were well preserved, hence their form and structure are well known.
- The plant grew in swampy marshes. It was differentiated into horizontally creeping rhizome and an upright branched shoot without leaves.
- There were no roots. Unicellular rhizoids were borne in patches, on underside of the rhizome.
- The upright branches were dichotomously branched and gradually tapering. The sporangia terminated these branches.
ANATOMY OF RHIZOME AND AERIAL SHOOT
- Both aerial branches and rhizome were differentiated into epidermis, cortex and stele.
- The epidermis was cuticularized with stomata scattered on the aerial shoot. They were absent from the rhizome.
- The cortex was differentiated into outer and inner zone.
- The outer cortex was only 1-4 layered and had compact parenchymatous cells.
- The inner cortex had spherical cells with large intercellular spaces. The inner cortex is believed to be the chief photosynthetic region of the plant.
- The stele was a typical protostele with xylem completely surrounded by phloem.
REPRODUCTIVE ORGAN OF RHYNIA
- It was nearly oblong in shape, broad at the base and pointed at the apex.
- The wall of the sporangium was several layered, of which two could be easily distinguished.
- The outer wall was cuticularized and the innermost acted as tapetum.
- Inside the sporangium were spores, all of which were of the same size. Spores in tetrads were also seen in some specimens.
- Columella was absent from the sprangium.
IDENTIFICATION OF RHYNIA
- DIVISION – Pteridophyta
- True roots generally present (except in Psilopsida),
- True vascular strand present.
- Sub-division :- Psilophytopsida
- True roots absent.
- Shoot differentiated into subterranean rhizome and apical portion.
- Sporangia borne terminally.
- Order – Psilophytales
- Sporophyte dichotomously branched.
- Sporangia generally borne singly.
- Family – Rhyniaceae
- Rhizoids unicellular, on rhizomes.
- Aerial portion leafless.
- Genus – Rhynia
- Subterranean portion not corm-like.
- No columella in sporangia.
- Text book of practical :- botany