Baragwanathia
Encyclopedia
Baragwanathia is a genus of extinct plants of the division Lycopodiophyta
of Late Silurian
to Early Devonian
age , fossils of which have been found in Australia, Canada and China.
in the presence of vascular tissue in its leaves - Asteroxylon has vascule-free enations. It is set apart from the closely related genus Drepanophycus
, of the same period, in the position of the sporangia and the arrangement and shape of the leaves. (See Drepanophycaceae
for more details.) These extinct terrestrial vascular plant
s had stems varying in diameter and length (up to a few cm for the diameter and a few metres for the length). They were erect or arched, dichotomized occasionally, and were furnished with true roots at the base. Vascular bundle actinostele
, tracheid
s of primitive annular or helical type (so-called G-type). Leaves were unbranched strap-shaped microphyll
s 1-2 cm long with a single prominent vascular thread, arranged spirally on the stem. Sporangia
axillary (exact position not known), broader than long, dehiscing by a slit on top. Spore
s were trilete; the gametophyte is currently unknown. The name apparently derives from William Baragwanath, director of the Victorian Geological Survey
at the time of discovery.
Lycopodiophyta
The Division Lycopodiophyta is a tracheophyte subdivision of the Kingdom Plantae. It is the oldest extant vascular plant division at around 410 million years old, and includes some of the most "primitive" extant species...
of Late Silurian
Silurian
The Silurian is a geologic period and system that extends from the end of the Ordovician Period, about 443.7 ± 1.5 Mya , to the beginning of the Devonian Period, about 416.0 ± 2.8 Mya . As with other geologic periods, the rock beds that define the period's start and end are well identified, but the...
to Early Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
age , fossils of which have been found in Australia, Canada and China.
Description
Baragwanathia is a primitive lycopod, differing from such taxa as AsteroxylonAsteroxylon
Asteroxylon is an extinct genus of plants of the Division Lycopodiophyta known from anatomically preserved specimens in an Early Devonian deposit of chert at Rhynie, Aberdeenshire in North-East Scotland that has been dated at...
in the presence of vascular tissue in its leaves - Asteroxylon has vascule-free enations. It is set apart from the closely related genus Drepanophycus
Drepanophycus
Drepanophycus is a genus of extinct plants of the Division Lycopodiophyta of Early to Late Devonian age , found in Eastern Canada and Northeast USA, China, Russia, Egypt and various parts of Northern Europe and Britain.-Description:...
, of the same period, in the position of the sporangia and the arrangement and shape of the leaves. (See Drepanophycaceae
Drepanophycaceae
Drepanophycaceae is a family of extinct plants of the division Lycopodiophyta of Late Silurian to Late Devonian age , found in North America, China, Russia, Europe, and Australia.-Description:...
for more details.) These extinct terrestrial vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...
s had stems varying in diameter and length (up to a few cm for the diameter and a few metres for the length). They were erect or arched, dichotomized occasionally, and were furnished with true roots at the base. Vascular bundle actinostele
Stele
A stele , also stela , is a stone or wooden slab, generally taller than it is wide, erected for funerals or commemorative purposes, most usually decorated with the names and titles of the deceased or living — inscribed, carved in relief , or painted onto the slab...
, tracheid
Tracheid
Tracheids are elongated cells in the xylem of vascular plants that serve in the transport of water and mineral salts. Tracheids are one of two types of tracheary elements, vessel elements being the other. All tracheary elements develop a thick lignified cell wall, and at maturity the protoplast...
s of primitive annular or helical type (so-called G-type). Leaves were unbranched strap-shaped microphyll
Microphyll
The terminology of fossil plants is in places a little confusing. In the discipline's 200+ year history, certain concepts have become entrenched, even though improved understanding has threatened the foundations upon which they are based...
s 1-2 cm long with a single prominent vascular thread, arranged spirally on the stem. Sporangia
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
axillary (exact position not known), broader than long, dehiscing by a slit on top. Spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s were trilete; the gametophyte is currently unknown. The name apparently derives from William Baragwanath, director of the Victorian Geological Survey
Geology of Victoria
Victoria is an Australian state, situated at the southern end of the Great Dividing Range. The Great Dividing Range stretches along the east coast of the continent and terminates near the Victorian city of Ballarat west of the capital Melbourne, though the nearby Grampians may be considered to be...
at the time of discovery.