Juncus dichotomus
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''Juncus dichotomus'' (commonly known as forked rush) is a
monocot Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...
in the
Juncaceae Juncaceae is a family of flowering plants, commonly known as the rush family. It consists of 8 genera and about 464 known species of slow-growing, rhizomatous, herbaceous monocotyledonous plants that may superficially resemble grasses and s ...
family of rushes. The plant is native to the Americas in temperate zones but has been introduced to other parts of the world. ''Juncus dichotomus'' often is found in very moist areas and where rainfall is a common occurrence. It is often most recognizable in the spring and summer months due to its conspicuous flowers and
infructescence Infructescence (fruiting head) is defined as the ensemble of fruits derived from the ovaries of an inflorescence. It usually retains the size and structure of the inflorescence. In some cases, infructescences are similar in appearance to simple fru ...
. The species can be difficult to identify and is often confused with other ''Juncus'' species due to morphological similarity. Often ''Juncus dichotomus'' is overlooked because it is inconspicuous in the field. It is sometimes considered a weed.


Description

''Juncus dichotomus'' is a
graminoid In botany and ecology, graminoid refers to a herbaceous plant with a grass-like morphology, i.e. elongated culms with long, blade-like leaves. They are contrasted to forbs, herbaceous plants without grass-like features. The plants most ofte ...
, i.e., a grass-like plant. It belongs to the monocot group in which it is a member of a Juncaceae family, otherwise known as the rushes. This species of rush is not tall and lacks many distinctive features, making it especially hard to identify by non-specialists. In North America, ''Juncus dichotomus'' is most frequently observed in July through August. It can be found in dry sites, but it thrives best in damp soils, such as roadside ditches where runoff is frequent.


Habitat and distribution

''Juncus dichotomus'' is native and distributed widely in the Americas in
temperate zones In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
but has been reported as introduced in other temperate climate zones around the world. The species is common throughout the southeastern United States, and in some northeastern regions. ''Juncus dichotomus'' is a more specialized species, found in temporarily wet habitats: riverbanks, pond margins, depressions in heaths, sometimes near rice fields. It usually grows in sandy soils, or any habitat that holds sufficient groundwater with stable temperate temperatures. Flowering and fruiting occur in late spring–summer in ditches, shores, clearings, and other typically open areas, usually in sandy, well-drained (but frequently wet) soil.


Taxonomy

''Juncus dichotomus'' is a perennial herb, with stems (10–)15–40 cm tall and usually reddish at the base. Its
rhizomes In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
are densely branched to short-creeping. It has 2–3 basal or sub-basal leaves which are nearly
terete Terete is a term in botany used to describe a cross section that is circular, or like a distorted circle, with a single surface wrapping around it.Lichen Vocabulary, Lichens of North America Information, Sylvia and Stephen Sharnoff/ref> This is us ...
, channeled or flat, 10–25(–40) cm long and about 0.7 mm wide; its auricles are very short, 0.2–0.5 mm in length, with a scarious to leathery texture and white to faint purple color. Its
inflorescences An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
are terminal with (5–)10–85(–100) flowers, which are often congested but more rarely somewhat loose. Flowers are
bracteoles In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves. They may be smaller, larger, or of ...
with green
tepals A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...
. Capsules are tan to brown, and are ellipsoid to wide in shape. Seeds are brownish to amber, ellipsoid to lunate in shape, about 0.3–0.4 mm in size.


Uses

The uses for ''Juncus dichotomus'' are limited. Since the plant is often found near water sources, it can play a role in preventing erosion.


Management

It is clear that ''Juncus dichotomus'' has increased its range substantially due to human aided dispersal. However, the biogeographic history of the species is somewhat unclear due in part to its similarities with other graminoid species. ''Juncus dichotomus'', a native of the Americas, is also now being reported as invasive in Europe. ''Juncus dichotomous'' has been confused with ''
Juncus tenuis ''Juncus tenuis'', the slender rush, is a clump-forming, round-stemmed perennial in the Juncaceae (rush family). Slender rush grows to be between 15 and 60 cm tall. Generally considered a weed, it is rarely sold by retailers as a household ...
,'' a related plant widespread in Europe which may have contributed to its spread there. Management of this species as an invasive in Europe is unclear, although water regime is important and may be manipulated to control the plant, in addition to herbicides. Systemic rusts and smuts have a major effect on individual plants and populations, as these fungi affect growth and survival; diseased plants may become distorted, stunted, or elongated, although the results are variable. More work on the life history of ''J. Dichotomus'' is required to better understand how it responds to disease and other abiotic factors.


References

{{Taxonbar, from=Q15505832 dichotomus Flora of North America Flora of Central America Flora of South America Plants described in 1817