''Enhalus'' is a monotypic genus of marine

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s. The sole species is ''Enhalus acoroides''. ''Enhalus'' is a large

seagrass Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...

native to coastal waters of the tropical Indian and Western Pacific Oceans. It is the only species of seagrass that does aerial surface pollination in which the pollen and the styles remain dry.Phillips, R.C. and E.G. Meñez. 1988. Seagrasses. Smithsonian Contrib. Mar. Sci. 34, 104 pp. ''Enhalus'' is surface pollinated with male

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s that detach from the plant to float on the surface until they reach a female flower where pollination can occur. Enhalus acoroides is considered a slow-growing, "

climax Climax may refer to: Language arts * Climax (narrative), the point of highest tension in a narrative work * Climax (rhetoric), a figure of speech that lists items in order of importance Biology * Climax community, a biological community th ...

" species.

Description

''Enhalus acoroides'' massive rhizomes (1.5 cm in diameter) help it stay anchored in soft mud substrates, withstanding wave action and tidal currents. it has long strap like leaves (30–150 cm) which make up a significant volume of total plant biomass of shallow water seagrass beds, because of the large structure of the leaves and where they are in the water column, they provide greater surfaces for

Epibiont An epibiont (from the Ancient Greek meaning "living on top of") is an organism that lives on the surface of another living organism, called the basibiont ("living underneath"). The interaction between the two organisms is called epibiosis. An ep ...

organisms to inhabit. Fruit are round and large (4–6 cm in diameter) with dark, ribbed skin and 6-7 white seeds. The male plant bears a single pedunculate

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

or stem containing clusters of flowers, each is highly reduced in form to a small free floating device. Female Enhalus acoroides bears only a single inflorescence, but the peduncle of a female flower is much longer.

Distribution and habitat

''Enhalus acoroides'' is a

littoral The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely i ...

species living in shallow soft substrates like muddy or sand-flats and coral substrates depending the region of growth. It can be found as far east as

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

and can range from the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

south to northern Mozambique in the Indian Ocean. It can be found in mixed meadows of seagrasses comprising 90% of the meadow biomass mainly with ''Thallassia hemprichii.'' it can also be found living in isolated areas. Enhalus acoroides grows best just above the level of mean low water springs and grows to generally 4 meters deep.

Reproduction

''Enhalus acoroides'' is

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

and able to reproduce sexually and asexually. ''Enhalus acoroides'' create small isolated patches containing 25 to 200 shoots through lateral rhizome spreading. It can also produce pollen like other seagrasses but it is unique in that it is the only species of seagrasses that surface pollinates. During this process, the male flower will break off from the

spathe In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also look ...

and rise to the surface where it has numerous flowers inside its hydrophobic

s. Once at the surface it will release its pollen to a female inflorescence where it has reached the surface of the water by means of an elongated stalk surface. The developing fruit is drawn under the water to finish ripening. Flowering is a year round phenomenon and the amount of flowers being produced are strongly related to variations in mean water temperatures.

References

External links

*
Images
of ''Enhalus'' at

AlgaeBase AlgaeBase is a global species database of information on all groups of algae, both seaweed, marine and freshwater algae, freshwater, as well as sea-grass. History AlgaeBase began in March 1996, founded by Michael D. Guiry, Michael Guiry. Text ...

{{Taxonbar, from=Q2697339 Hydrocharitaceae Seagrass Hydrocharitaceae genera Monotypic Alismatales genera Dioecious plants