Perennial fern ally 3 - 9 cm tall Leaves: of upright stems spreading, stalkless, green, 5 - 6 mm long, 0.5 - 0.8 mm wide, linear to lance-shaped, and usually non-toothed. Spores: hundreds per sac, all of one kind, thick-walled, wrinkled, three-sectioned (trilete) with pointed angles. The spores give rise to the gametophyte (the sexual phase of the plant), which is small, pincushion-shaped, green, photosynthetic, and on substrate surface rather than buried. Upright stems: usually single, but sometimes two from same node, unbranched, green, leafy, and more slender than horizontal stem (4 - 7 mm diameter). Horizontal stem: on top of soil or substrate surface, 3 - 12 cm long, slender (5 - 9 mm diameter; excluding leaves only 0.5 - 0.9 mm), covered with spreading, upcurved, 5 - 6 mm long, 0.5 - 0.7 mm wide, non-toothed, linear leaves, and also with slender roots emerging on underside of stem.
Similar species: Lycopodiella inundata is a bit different from our other species of Lycopodiella since it is so small. The other two species in the Chicago Region, L. margueritae and L. subappressa, are typically at least 9 cm tall, the horizontal stems (excluding leaves) are over 1 mm in diameter, their strobili are usually over 2 cm long, and the sporophylls are appressed. Sterile hybrids between these two species and L. inundata have also been reported in the Chicago Region.
Habitat and ecology: Rare, typically now only in sand pits or other sandy habitats that have been excavated down to the water table in our eastern counties. However, this species could also be expected in bogs, lake shores, and marshes.
Occurence in the Chicago region: native
Notes: This species has the most expansive range of all Lycopodiella in the northern half of North America. It has a disrupted range in the central part of the continent to our west. Species of Lycopodiella hybridize freely, and when the parent species have the same ploidy level the hybrids are fertile. Lycopodiella inundata can hybridize with the other two species of the Chicago Region, L. subappressa and L. margueritae, but since they are of a different ploidy level, the hybrids are sterile. The most common species in the Chicago Region is probably L. margueritae.
Etymology: Lycopodiella is a combination of the genus name Lycopodium, and the suffix ella, referring to the diminutive form (smaller) of this genus compared to Lycopodium. Inundata is Latin for "to cover with water".
Author: The Field Museum
From Flora of Indiana (1940) by Charles C. Deam
Very local. It grows in wet, somewhat acid sandy soil, usually on the borders of lakes and in the dunes. It has also been reported from Marshall County. I have twice found it associated with cranberry and hair-cap moss. In 1937 I revisited the Steuben County station and found that it has been exterminated there.