Nesaea

Scientific name

Nesaea Comm. Ex. Kunth

Common names

red-stem

Family

Lythraceae

Similar genera

Alternanthera, Ammannia, Cuphea, Hypericum, Ludwigia, Lythrum

Native distribution

tropical Africa, Asia, Central and South America, Australia

Species cultivated

Nesaea crassicaulis (Guill. & Perr.) Koehne

N. pedicellata Hiern

Adventive distribution

none

Weed status

not weedy

Habit

emergent emergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
stem plant

Brief description

Annual or perennialperennial:
(adj) (of a plant) having a life cycle of more than two years
. Stem erect or ascending, usually four-sided (when emersedemersed:
see emergent
). Leaves oppositeopposite:
(adj) (of leaves) two leaves per node; in pairs on opposite sides of an axis
, decussatedecussate:
(adj) arranged along stem in pairs, with each pair at right angles to the pairs above and below
, sessilesessile:
(adj) attached directly, without a stalk
, linear to ovateovate:
(adj) egg-shaped in outline; generally with the broad end at or near the base
; marginmargin:
(n) edge; rim
entireentire:
(adj) having a continuous margin that is not toothed or lobed
. Inflorescenceinflorescence:
(n) the arrangement of flowers on the floral axis
sessile or pedicellatepedicellate:
(adj) borne on a pedicel
. Flowers axillaryaxillary:
(adj) in, of, or produced from an axil
, solitary or in many-flowered headhead:
(n) inflorescence consisting of small closely packed stalkless flowers or florets arising at the same level on a flattened axis; of several types, including: discoid (composed entirely of disk flowers) and radiate (composed of central disk flowers and marginal ray flowers)
, actinomorphicactinomorphic:
(adj) of flowers, having radial symmetry; capable of being bisected into identifical halves along more than one axis
; sepals 4-5; petals 4-5, pink to purple. Dispersal by seeds or stem fragments.

Natural habitat

limestone seeps, river and creek banks, springs, margins of lakes, other marshy to damp areas

Additional comments

Nesaea contains over 50 species (six aquatic) with only two species commonly cultivated for aquaria. The genus is morphologically diverse in Africa. Nesaea and Ammannia are separated only with great difficulty based on presumed differences in capsule dehiscence. There is considerable variation in color from deep red to yellow shown in Nesaea spp. when grown submersedsubmersed:
see submerged
; the degree of color depends on light and nutrient levels. Nesaea pedicellata has approximately half of its stamens (4-5) longer than the calyxcalyx:
(n) the outer whorl of the perianth; all the sepals of a flower
and half (4-5) the same length. All of the stamens are the same length as the calyxcalyx:
(n) the outer whorl of the perianth; all the sepals of a flower
in N. crassicaulis. A gold leaf form of N. pedicillata is commonly traded and will revert back to the normal green form through occasional side shoots when grown emersedemersed:
see emergent
. Graham, et al. (2011) synonymized Nesaea with Ammannia, although it remains commonly traded under the name of Nesaea.