Isoetes engelmannii
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| Isoetes engelmannii | |
|---|---|
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Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Lycophytes |
| Class: | Lycopodiopsida |
| Order: | Isoetales |
| Family: | Isoetaceae |
| Genus: | Isoetes |
| Species: | I. engelmannii |
| Binomial name | |
| Isoetes engelmannii | |
| Synonyms[2] | |
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Calamaria engelmannii (A.Braun) Kuntze | |
Isoetes engelmannii is a species of aquatic plant in the family Isoetaceae.[2] It is referred to by the common names Engelmann's quillwort or Appalachian quillwort (not to be confused with the newly described Isoetes appalachiana), and is the most widely distributed species of its genus in eastern North America. Its range extends from Ontario in the north, south to Florida and west Arkansas and Missouri. It can be found from April to October in temporary pools, bogs, marshes, stream edges, swamps and along wet roadsides.
Isoetes engelmannii is an emergent aquatic perennial pteridophyte. The rootstock (rhizomorph) is almost globose and normally has 2 lobes. The bright green, pliable leaves are evergreen and become paler towards the base and gradually taper to a point at the apex. They are typically about 60 cm in length, but they range from 10 cm up to 90 cm long. They are arranged spirally. The wall of the sporangium typically lacks any pigment, but sometimes it may be streaked with brown. The velum covers less than a quarter of the sporangium. The megaspores are white in colour and measure 400 to 560 μm in diameter. Their texture is reticulate (i.e. net-like) and the lamellate ridges are unbroken. The girdle that runs between these ridges is obscured by the heavy reticulation. The microspores are grey in colour, measure 20 to 30 μm in diameter, and are smooth to papillose (i.e. with minute projections) in texture. The spores mature in the summer. The chromosome number is 2n = 22.[3]