Renalia
Encyclopedia
Renalia is a genus of extinct vascular plant
s from the Early Devonian (around ). It was first described in 1976 from compressed fossils in the Battery Point Formation (Gaspé, Québec, Canada).
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 dichotomized several times. Tracheid
s were present in the stems. The rounded to reniform (kidney-shaped) sporangia
(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
s were trilete.
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.
, 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 lycophytes
. Hence the position of the genus in the cladogram
for the polysporangiophyte
s which Crane et al. published in 2004; Renalia is placed basal to the lycophytes
(clubmosses and relatives).
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 from the Early Devonian (around ). It was first described in 1976 from compressed fossils in the Battery Point Formation (Gaspé, Québec, Canada).
Description
The species R. hueberi was described by Gensel in 1976 from compressed fossils. As with all compressions, it is difficult to reconstruct the entire plant, but the sporophyteSporophyte
All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants...
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 dichotomized several times. 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 were present in the stems. The rounded to reniform (kidney-shaped) 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...
(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
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.
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 tissueVascular tissue
Vascular tissue is a complex conducting 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. There are also two meristems associated with vascular tissue:...
, 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 lycophytes
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...
. Hence the position of the genus in the cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
for the polysporangiophyte
Polysporangiophyte
Polysporangiophytes, also called polysporangiates or more formally Polysporangiophyta, are plants in which the spore-bearing generation has a structure of branching stems terminating in sporangia...
s which Crane et al. published in 2004; Renalia is placed basal to the lycophytes
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...
(clubmosses and relatives).
External links
- Cladogram from
