Hygrophila (plant) explained

Hygrophila, commonly known as swampweeds,[1] [2] is a genus of flowering plants in the acanthus family, Acanthaceae. There are about 80[3] to 100[4] [5] species, of which many are aquatic plants. The genus is distributed across the tropical and subtropical world.[3] [4] It is one of only two genera in its family that contains aquatic plants, the other being Justicia. The genus is treated in 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, all with one form, or heteromorphic, with different forms on one plant. Homomorphic leaves are always simple and entire. Plants with heteromorphic leaves generally have pinnately divided basal leaves with either filiform (feather-like) or linear segments, and undivided leaves higher on the stem.

The flowers have white to purple corollas with either 5 equal lobes or 2 lips. A lipped corolla has an erect, concave upper lip with two lobes, and a lower lip with 3 lobes. The flower has four stamens. Two may be staminodal, lacking pollen. The individual filaments of the stamens are united into pairs by a membrane. There is an inconspicuous nectar disc. Each flower yields at least 6 seeds.

Ecology and uses

A number of Hygrophila species and cultivars are popular within the aquascaping and aquarium hobbies, including H. angustifolia, H. corymbosa, H. lancea 'Araguaia',[6] H. pinnatifida, H. difformis 'Water Wisteria', H. odora, H. polysperma 'Indian swampweed' and H. siamensis. Additionally, there are some striking newer forms on the market, such as the vivid hybrids of Hygrophila polysperma, 'Sunset'[7] and 'Rosanervig'.[8]

Many members of the genus are troublesome weeds if they become established within irrigation systems, drains or drainage ditches, as well as in rice fields. Several have become established outside of their native ranges, either due to accidentally-discarded cuttings or deliberate release, such as H. polysperma in the southern United States.

Species

77 species are accepted:

External links

Notes and References

  1. http://plants.usda.gov/core/profile?symbol=HYGRO Hygrophila.
  2. https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=34419 Hygrophila.
  3. http://www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=116043 Hygrophila.
  4. http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=116043 Hygrophila.
  5. Hài, Đ. V. and D. Đ. Huyến. (2012). New record of species Hygrophila episcopalis R. Ben. (R. Ben.) (Acanthaceae) for the flora of Vietnam. Journal of Biology 34(2), 187-89.
  6. Web site: Hygrophila Lancea 'Araguaia' . 10 March 2024 . BucePlant.com.
  7. Web site: Hygrophila polysperma 'Sunset' . 10 March 2024 . Dennerle Plants.
  8. Web site: Hygrophila polysperma Rosanervig . 10 March 2024 . aquasabi.

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