Huvenia is a genus of extinct plants of the Early Devonian (Pragian or Siegenian stage, around ), found in slate deposits of the Rhenish Massif. The sporophyte generation

Alternation of generations

Alternation of generations is a term primarily used in describing the life cycle of plants . A multicellular sporophyte, which is diploid with 2N paired chromosomes , alternates with a multicellular gametophyte, which is haploid with N unpaired chromosomes...

 consisted of leafless stems (axes), which appear to be flattened, and which branch dichotomously. The strand of conducting tissue contains simple 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, making this a 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...

 (tracheophyte). The sporangia (spore-forming organs) are borne on the ends of short branching stems (sporangiophores) rather than terminating main stems as in some other early land plants. Sporangia appear to be twisted, but it is not clear whether this feature was present in life or developed after death.

In 2004, Crane et al. published a 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, in which Huvenia is placed in the Rhyniaceae. (See that article for the cladogram.)