Najas graminea Delile

Ricefield waternymph (en), Naja de graminée (fr), Naïade (fr), Naïade graminée (fr)

Species

Angiosperms > Alismatales > Hydrocharitaceae > Najas

Characteristics

Up to 50(-75?) cm, lower internodes 1-10 cm, by (0.6-)0.7-1.5(-2.25) mm. Leaves (1¾-)2½-3½(-6)cm by (0.6-)0.7-1 (-4) mm, flat, seldom canaliculate, apex obtuse (-rounded), rarely somewhat acute (blade c. 3 mm below the tip 0.4-1.2 mm wide); margin on either side with (40-)60(-185) inconspicuous spiny teeth, mainly consisting of the spine-cell; dorsal surface without spines; spine-cells 0.05-0.15 mm, yellowish brown; midrib c. 0.07-0.05 times as wide as the blade, cavities occupying up to 1/4 of the width of the blade, septa (+-) indistinct. Sheath (3-)4-5(-10.5) by (2-)3-4(-8.5) mm, on either side with (10-)15-30(-50) spines; 3-8 spines on the inner edge of the auricle; auricles long-triangular, seldom slightly falcate; apex acute, rarely obtuse or acuminate, (1-)2(-5.5) by 0.5-1(-1.5) mm, entire, rarely (shallowly) lobed. Flowers often up to 3 together, in different stages, together with one male, or male solitary (in the var. robusta all flowers probably solitary). Male flowers: spathe 0; anther 4(-2)-celled, elliptical, rarely ovate or oblong, (1-)1.5(-2) by (0.4-)0.7(-1) mm; 'perianth lobes' distinct, rounded to globular. 'Pedicel' 0.2-0.5 mm, at anthesis (0.7-)1-2.5 mm. Female flowers: no spathe; (1.6-)2(-3.5) mm; ovary (0.6-)0.7(-1) by (0.2-) 0.35(-0.4) mm; style (0.4-)0.7(-1.2) mm, with (1-)2(-3) stigmas (0.4-)0.8(-1.6) mm. Seeds (in the var. robusta unknown) (1.6-, broad seeds) 2.3(-2.7) by (0.6-, long seeds) 0.8(-0.9) mm; testa with 20-34 length-rows of 30-45 subquadrate to 5-6-angular areoles (often slightly higher than broad).
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Stems sparingly branched distally, to 35 cm ´ 0.2--0.5 mm; internodes 0.4--1.9 cm, without prickles. Leaves spreading to ascending with age, 0.8--2 cm, lax in age; sheath 1--1.5 mm wide, apex deeply auriculate; blade 0.5--1 mm wide, margins minutely serrulate, teeth 40 per side, apex acute with 2--3 teeth, teeth unicellular; midvein without prickles abaxially. Flowers 1--2 per axil, staminate and pistillate on same plants. Staminate flowers in distal axils, 2--3 mm; involucre beaks 4-lobed, 1--1.5 mm; anther 4-loculed, 1.5 mm. Pistillate flowers distal to proximal, to 3.5 mm; styles to 1 mm; stigmas 2-lobed. Seeds not recurved, greenish brown, fusiform, 1.7--2.5 ´ 0.4--6 mm, apex with style situated at center; testa dull, 3 cell layers thick, pitted; aeroleareoles regularly arranged in 35 longitudinal rows, not ladderlike, 4-angled, as long aser than broad, end walls slightly raised. 2n = 24, 36, 48 (Asia).
Stems 10-20 cm tall, 0.5-1 mm in diam. Leaves narrowly linear to linear, 1-2.5 cm × 0.4-1 mm; sheath 1.5-3 mm, deeply auriculate; auricles narrowly triangular or lanceolate, 1-2 mm, serrulate with several teeth on each side, apex acute; leaf margin minutely and densely serrulate with 30-50 inconspicuous teeth on each side, consisting of brownish spine cells only. Plants monoecious; flowers solitary, or sometimes 2 or 3 together. Male flowers usually more toward upper axils, ca. 1 mm, elliptic; spathe absent; anther 4-thecous. Female flowers 1.5-2 mm; style ca. 1 mm; stigmas 2-4-lobed. Fruit oblong, 1.5-2 × ca. 0.8 mm. Seeds ellipsoid-oblong, with ca. 30 rows of pits; areoles hexangular and irregularly polygonal toward ends, or rectangular. Fl. and fr. Jun-Sep. 2n = 12*, 24, 36*, 48, 72.
Small, unarmed plants with much branched shoots, 10-60 cm long, often plumose above because of the closely packed leaves. Roots many, long, filiform, with a dense covering of long root-hairs towards the tip. Stems with terete, brittle internodes, 1 mm in diam. Leaves 16-25 mm long, 0.5-6 mm wide, teeth microscopic, about 40-55 on each side; sheaths with linear-setaceous auricles about 1.5 mm long, bearing some minute teeth. Flowers monoecious. Male flowers solitary, in upper leaf axils, naked; pedicel at anthesis 1 mm long, anther 1 mm long, oblong, apically with 2 small obtuse ridges. Female flowers usually in lower axils, sessile, about 1.5 mm long, the ovary about as long as the short style and the 2 long stigmatic arms. Fruit oblong, 1.5 mm.
An annual herb. It attaches to the ground but grows underwater in freshwater lakes. The stems are 35-40 cm long and 0.7 mm thick. The leaves are 14-25 mm long and 1 mm wide. There are 2-3 teeth at the tip.
Perennial aquatic herb, shoots 100-600 mm long. Stems smooth, herbaceous. Leaves filiform with 40-60 microscopic teeth, septa of leaf distinct. Stigmas 2. Flowers green.
Life form annual
Growth form herb
Growth support aquatic
Foliage retention -
Sexuality monoecy
Pollination hydrogamy
Spread hydrochory
Mature width (meter) -
Mature height (meter) 0.15 - 0.2
Root system -
Rooting depth (meter) -
Root diameter (meter) -
Flower color
Blooming months -
Fruit color -
Fruiting months
JanFebMar
AprMayJun
JulAugSep
OctNovDec
Nitrogen fixer -
Photosynthetic pathway -

Environment

Chiefly in the lowland in rice-fields, ditches, small streams, inbotheverwetand seasonal areas, up to 400 m, rarely at 1000 m (W. Java), once at 1400 m (Wetar), often together with Nitella, Salvinia, Mars ilea, Pistia, and other aquatics. By BRANDIS noted to occur in a hot spring in Burma at 92° F.
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Ponds, paddy fields, usually in still or slowly-moving waters. Rice fields and ditches. Found in one pond in Britain that is warmed by industrial outflow.
It is a tropical and temperate plant. It can tolerate water to 33°C.
Light 4-9
Soil humidity 10-12
Soil texture 1-6
Soil acidity 3-7
Soil nutriment -
Hardiness (USDA) 7-10

Usage

Uses -
Edible leaves
Therapeutic use -
Human toxicity -
Animal toxicity -

Cultivation

Can be grown by seedlings.
Mode seedlings
Germination duration (days) -
Germination temperacture (C°) -
Germination luminosity -
Germination treatment -
Minimum temperature (C°) -
Optimum temperature (C°) -
Size -
Vigor -
Productivity -

Images

Najas graminea unspecified picture

Distribution

Najas graminea world distribution map, present in Afghanistan, Argentina, Australia, Bangladesh, Bulgaria, Brazil, Botswana, Central African Republic, China, Algeria, Egypt, Spain, Ethiopia, France, United Kingdom of Great Britain and Northern Ireland, Gambia, Guinea-Bissau, Greece, Indonesia, India, Iran (Islamic Republic of), Iraq, Italy, Japan, Kazakhstan, Kenya, Moldova (Republic of), Mali, Myanmar, Mauritania, Malaysia, Nepal, Oman, Pakistan, Philippines, Palau, Korea (Democratic People's Republic of), Romania, Rwanda, Sudan, Senegal, Somalia, Turks and Caicos Islands, Chad, Thailand, Taiwan, Province of China, Tanzania, United Republic of, United States of America, Uzbekistan, Viet Nam, Yemen, and South Africa

Conservation status

Najas graminea threat status: Least Concern

Identifiers

LSID urn:lsid:ipni.org:names:603012-1
WFO ID wfo-0000769492
COL ID 45KZB
BDTFX ID 43482
INPN ID 109208
Wikipedia (EN) Link
Wikipedia (FR)

Synonyms

Najas graminea Caulinia graminea Najas seminuda Najas graminea var. serristipula Najas graminea var. vulgata Caulinia fragilis var. intermedia

Lower taxons

Najas graminea var. graminea Najas graminea var. recurvata