Hygrophila

Taxobox


image_width = 200px
image_caption = "Hygrophila polysperma" in an aquarium
name = "Hygrophila"
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Lamiales
familia = Acanthaceae
genus = "Hygrophila"
genus_authority = Lindl.
subdivision_ranks = Selected species
subdivision =
*"Hygrophila corymbosa"
*"Hygrophila difformis"
*"Hygrophila polysperma"

"Hygrophila", commonly known as the temple plants or hygros, is a genus of flowering plants in the family Acanthaceae. There are about 125 species, of which about 40 are aquatic. The genus has a pan-tropical distribution, with some members entering sub-tropical areas. It is one of only two genera in its family that contains aquatic plants, the other being "Justicia". The genus is treated inside the tribe "Hygrophileae", which is noted as being in need of revision at the genus level, meaning the current taxonomic boundaries of "Hygrophila" are likely to change in the future.

Description

The leaves are either homomorphic (i.e. all having one form) or heteromorphic (i.e. different leaves having different forms). When they are homomorphic, they are always simple and entire. When heteromorphic, the basal or submerged leaves are pinnately divided with either filiform (i.e. feather-like) or linear segments that can be either simple or forked, while the cauline leaves (i.e. those on the stem) or emergent leaves are entire.Citation| last =Cook| first =Christopher D.K.| title =Aquatic Plant Book| place=Amsterdam| publisher =SPB Academic Publishing| year =1996| edition =2| isbn =90-5103-132-7 ]

The flowers have petals ranging from white to purple in colour, having either 5 equal lobes or 2 lips. When an upper lip is present, it is erect and concave with either 2 lobes or 2 teeth, while the lower lip has 3 lobes. 4 stamens are present with 2 sometimes being staminodal (i.e. non pollen producing). They are not exerted and are fused to the petal tube above the middle. The individual filaments are united into pairs by a membrane at their bases, while the anthers have 2 locules. The anther sacs have no spurs or tails and are at the same level and parallel. A nectariferous disc is present but inconspicuous. Pollen grains are 3- or rarely 4-colporate, meaning the apertures are composed of both a colpus and a porus. Each flower produces 6 to many seeds.

Ecology and uses

A number of species are cultivated for the aquarium trade, including "H. difformis" (water wisteria) and "Hygrophila polysperma" (Indian swampweed). Many members of the genus are troublesome weeds in irrigation and drainage ditches as well as rice fields. Several have become established outside of their native ranges, largely due to the aquarium trade, such as "H. polysperma" in the southern United States.

References

External links

*commons-inline
* [http://www.aqualandpetsplus.com/Decor%20Hygrophila.htm Decorating with Fast-Growing Hygrophila Plants]
* [http://www.thekrib.com/Plants/Plants/Hygrophila.html Krib]