''Isoetes engelmannii'' is a species of

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

in the family Isoetaceae. 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 North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. 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.

Description

''Isoetes engelmannii'' is an emergent aquatic perennial

pteridophyte A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. Ferns, ...

. The rootstock (rhizomorph) is almost globose and normally has 2 lobes. The bright green, pliable

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

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 A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cy ...

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.

Distribution and habitat

''Isoetes engelmannii'' is widely distributed in eastern

, more so than any other species in the genus occurring in that region. Within Canada it is only found in the extreme southern portions of Ontario. In the United States its primary range begins in New Hampshire in the northeast and west to

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

. There are also several outlying populations farther west in western Michigan. The range extends south along the Appalachians to the extreme north of Florida, and also continues west in the mountains to the northeastern tip of Mississippi, the northeastern tip of Arkansas and southeastern Missouri, and north to the southern portions of Indiana and Illinois. Another disjunct population exists in northeastern Ohio. It can be found from April to October in habitats that include temporary pools, bogs, marshes, in streams or along their edges, swamps and along wet roadsides in ditches. It also grows as an emergent in shallow lakes and ponds.

References

External links

Profile at USDA PLANTS DatabaseRange Map from Flora of North AmericaIllustration from Flora of North America
{{Taxonbar, from=Q6085655 engelmannii Flora of the Eastern United States Plants described in 1846 Taxa named by Alexander Braun