''Renalia'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of extinct

vascular plant Vascular plants (), also called tracheophytes (, ) or collectively tracheophyta (; ), are plants that have lignin, lignified tissues (the xylem) for conducting water and minerals throughout the plant. They also have a specialized non-lignified Ti ...

s from the

Early Devonian The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pr ...

(around ). It was first described in 1976 from compressed fossils in the Battery Point Formation (Gaspé, Québec, Canada). It is difficult to reconstruct the original form of the complete plant, but it appears to have consisted of leafless branching stems whose side branches had

sporangia A sporangium (from Late Latin, ; : sporangia) is an enclosure in which spores are formed. It can be composed of a unicellular organism, single cell or can be multicellular organism, multicellular. Virtually all plants, fungus, fungi, and many ot ...

(spore-forming organs) at their tips. It is regarded as an early relative of the

lycophytes The lycophytes, when broadly circumscribed, are a group of vascular plants that include the clubmosses. They are sometimes placed in a division Lycopodiophyta or Lycophyta or in a subdivision Lycopodiophytina. They are one of the oldest lineage ...

(clubmosses and relatives).

Description

The

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

''R. hueberi'' was described by Patricia G. Gensel in 1976 from compressed fossils. As with all compressions, it is difficult to reconstruct the entire plant, but the

sporophyte A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spo ...

is thought to have been about 30 cm tall, with bare stems (axes) up to 1.5 mm wide. The main stem had lateral branches which divided into two equal branches (dichotomized) several times.

Tracheid A tracheid is a long and tapered Lignin, lignified cell in the xylem of Tracheophyta, vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms also use another type of conductive cell, called vessel elements, to t ...

s (specialized cells serving the purpose of water transport) were present in the stems. The rounded to reniform (kidney-shaped)

(spore-forming organs) were born at the tips of the lateral branches and dehisced (split) along the distal margin into two equal parts. The

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s were trilete (multiple spores shared a common origin, and were in contact with each other). Two further species, ''R. grabertii'' and ''R. major'' were described later by Schweitzer. The sporangia are similarly reniform, differing in their placement. In ''R. major'', they are inserted laterally on the stem on small stalks, too short to be called branches.

Phylogeny

The absence of leaves, the presence of

vascular tissue Vascular tissue is a complex transporting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. T ...

, the terminal position of the sporangia and the form of the branching of the stems (pseudomonopodial) suggest a relationship with the Rhyniaceae; however, the shape of the sporangia and the form of their dehiscence suggest a relationship with the

. Hence the position of the genus in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

for the polysporangiophytes which Crane et al. published in 2004; ''Renalia'' is placed basal to the

(clubmosses and relatives).

References

External links

Cladogram
from {{Taxonbar, from=Q7312519 Early Devonian plants Prehistoric plant genera