Selaginella apoda (L.) Spring

Selaginella apoda, commonly known as meadow spikemoss, is a perennial lycophyte native to much of the eastern United States and parts of northeastern Mexico. The life cycle is the shortest of the genus Selaginella, as well as one of the shortest among the lycophytes. Selaginella apoda is found primarily in damp soils in habitats such as swamps, wet fields, open woods and along stream banks. Selaginella apoda presents the potential for case studies involving the plant's adaptability to environmental toxins. It is closely related to Selaginella eclipes and S. ludoviciana, with both of which it has been reported to form hybrids. This group is characterized by relatively flat strobili and large megasporophylls which occur in the same plane as the lateral leaves.

The plant was originally described, and named Lycopodium apodum by Carl Linnaeus in his Species Plantarum (1753).

Description

Selaginella apoda stems have smaller leaves in two rows as well as larger leaves in two rows. This species can be differentiated from a regular moss species based on its veins running along the leaves. The stem of S. apoda can best be described as leafy. Selaginella species possess rhizophores.

Many species in the genus Selaginella also demonstrate dichotomous branching. Vegetative leaves on S. apoda are lined with small teeth, have a scale-like appearance, are short in length, and change in shape and size in the same node. Selaginella apoda branches can be a maximum of 15 centimeters in height and have a creeping style. The ligule on Selaginella species can be found rising on the adaxil surfaces of leaves at their base, as well as on sporophylls. The shape of the ligule is awl-shaped and occurs singly. The leaves of S. apoda contain a cuticle layer on their adaxial surfaces and they do not have hairs on their abaxial surfaces.

The internodes of S. apoda branches can be used to classify the branches as reproductive or vegetative, as the internodes are extended on vegetative branches. Selaginella apoda adventitious and primary roots contain a root cap at their tips, have the ability to branch when growing, are white, and possess root hairs, located in close proximity to the tips. Selaginella apoda primary root system contains only three single root strands; as such, the system is ailing, for it also does not branch significantly. Adjacent to the axil, sporangia are created from artificial cells. While stomata can be found following the leaf margin on the lower surface of the plant's leaves, stomata on the upper surface of S. apoda leaves disperse entirely  following the laminae.

The dorsal leaves of S. apoda have acuminate apices. The primary leaves of S. apoda significantly contrast in shape from the cotyledons of the plant. Selaginella apoda leaf blades have borders with a margin that is light green in appearance or simply identical to each other. The strobilus of S. apoda is often restricted to a length of 1-2 centimeters. Typically, the strobili of S. apoda are in an erect position. Within the sporangia, the two gametophyte forms start development. Selaginella apoda sporangia can be distinguished from other species of Selaginella in how its wall is composed of two layers instead of three.

Selaginella apoda - Wikipedia

Occurrence 4980447446 (gbif.org)