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Myriophyllum heterophyllum In water

Myriophyllum heterophyllum, popularly known as variable-leaved water milfoil, is a species of water milfoil.

Plants of Myriophyllum heterophyllum (variable-leaf watermilfoil)

Introduction:

A submerged herbaceous perennial aquatic plant with a small, emergent flower spike above the waterline. Submerged leaves (2-4.5 cm long) are pinnately split into 4-10 leaflet pairs, giving them a feathery appearance, and are grouped in whorls of 4-6 around a sturdy stem (3 mm in diameter).

. The stem may grow up to 3 mm (0.12 in.) thick and 1-3 m (3-10 ft.) long. The stems are formed from a rhizome that is rooted in the lake's bottom, and they can grow so long that the upper sections create a tangled mat near the surface in some circumstances. The whorled leaves are 2-4 cm (0.8-1.6 in.) long and rarely more than 1.5 cm (0.6 in.) apart on the stem. Each leaf is made up of 4-10 threadlike segments. The blooms are on a strong spike that reaches 5-15 cm (2-6 in.) above the water's surface. The bracts that encircle the male flowers are highly serrulate and much outnumber the blooms in length. This final characteristic distinguishes it from the ordinary M. sibiricum (shortspike watermilfoil).

Description and spread history:

M. heterophyllum has been discovered in five lakes in Minnesota, ranging in size from 104 to 145 hectares (256-355 ac.). Plants were discovered at depths ranging from 1-2 m in both clear and dark-stained water (3.3-6.6 ft.). Sand, gravel, and silt were among the substrates.

M. heterophyllum is widely thought to be native to the Eastern United States, with a range extending throughout the southern area and westward to North Dakota in the north.

There is relatively little available information on M. heterophyllum's biology and life cycle. The stems and leaves of this plant, like others in its genus (Myriophyllum; watermilfoil), grow underwater, while the flowering spikes emerge above the water. The blooms are unisexual and attract flying insects, which serve as pollination vectors. Although seed dispersal has not been verified, water currents and presumably aquatic creatures, notably birds and mammals, are expected to aid in the process. It is also thought that the species can spread by vegetative means. This would occur when a stem fragment (with leaves) is carried by water currents or an aquatic animal to a previously unoccupied habitat. Such fragments may, under certain conditions, have the capacity to produce roots or new stems.

It has been reported (fide Aitken 1981) that at a site where M. heterophyllum occurred, receding water stranded a colony of M. heterophyllum. When this happened, the plants survived in a terrestrial form that was characterized by tiny shoots, rarely over 10 cm (4 in.) high, and cutinized leaves, which are resistant to drying. Although this terrestrial form presumably does not produce flowers or fruits, it probably allows the survival of individuals, and perhaps whole populations, in years when the water level is unusually low.

Conservation / Management Of Plant

M. heterophyllum numbers should be thoroughly monitored on a yearly basis, if practicable. This would necessitate determining the population's geographical extent and density as precisely as feasible. If the populations are tiny, a comprehensive mapping of the population borders should be carried out. If the populations are big or dispersed, sampling procedures such as transects may be required.

Assuming M. heterophyllum is native to Minnesota (as is often assumed), and if populations begin to drop, and that reduction is proved to be the consequence of human action rather than natural fluctuation, the problem must be alleviated.\

Refrences:

Plant, I. (n.d.). Twoleaf watermilfoil: Myriophyllum heterophyllum ... twoleaf watermilfoi: Native Habit: Aquatic Plants Myriophyllum heterophyllum. Retrieved December 14, 2021, from https://www.invasiveplantatlas.org/subject.html?sub=12803

Aiken, S. G. A conspectus of Myriophyllum (Haloragaceae) in North America. Brittonia 33(1):57-69. Crow, G. E., and C. B. Hellquist. 2000. Aquatic and wetland plants of northeastern North America. Volume 1. Pteridophytes, Gymnopserms, and Angiosperms: Dicotyledons. University of Wisconsin Press, Madison, Wisconsin. 448 pp. Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp. NatureServe. 2015. NatureServe Explorer: an online encyclopedia of life [web application]. Veresion 7.1. NatureServe, Arlington, Virginia. Accessed 22 August 2016. Robert W. Freckmann Herbarium. 2009. Flora of Wisconsin: Consortium of Wisconsin Herbaria [web application]. University of Wisconsin, Stevens Point. <http://wisflora.herbarium.wisc.edu/>. Accessed 8 July 2009.