Najas guadalupensis (Spreng.) Magnus

Southern waternymph (en)

Species

Angiosperms > Alismatales > Hydrocharitaceae > Najas

Characteristics

Plants glabrous, monoecious (?). Stems 0.3-0.8 mm in diameter, profusely branched; lower internodes elongate (to 4 cm long), the upper internodes shortened (to 5 mm long or less). Leaves 1.2-2.8 cm long; laminas 1.2-1.8 mm wide, acute, mucronate, minutely serrulate with ca. 100 teeth per side, the mucro and 2 subterminal teeth larger than the lateral teeth, the teeth unicellular; auricles to 1.9 mm wide, barely wider than the laminas, only slightly flared below, with usually 7 teeth on the upper half of each side, none below, the teeth similar in structure to but larger than those of the laminas. Flowers solitary, the involucre light green with brown streaks; staminate flowers not seen; carpellate flowers to 1.5 mm long, the involucre above the ovary abruptly narrowed into a short beak, usually ending in 3 sharp-tipped lobes, the style ending in 2-3 stigmatic lQbes that extended above the involucral beak. Fruit 1.2-1.6 mm long and 0.4-0.6 mm wide, yellowish-white, fusiform, with a single basally flattened keel-like rib along which the involucre splits, the areolae inconspicuous, broader than long, to 0.2 mm long and 0.6 mm wide, (4-)6-angled, in ca. 20 longitudinal rows; seeds fusiform, greenish-white with 2 dark bands.
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Stems often profusely branched distally, 11--90 cm ´ 0.1--2 mm; internodes 0.1--9 cm, without prickles. Leaves spreading with age, 0.3--3.3 cm, lax in age; sheath 1--3.4 mm wide, apex rounded to truncate; blade 0.2--2.1 mm wide, margins minutely serrulate, teeth 18--100 per side, apex rounded to truncateslightly auriculate, with 1--3 teeth, teeth unicellular; midvein without prickles abaxially. Flowers 1--3 per axil, staminate and pistillate on same plants. Staminate flowers in distal axils, 1.5--3 mm; involucral beaks 4-lobed, 0.2--1.3 mm; anther 1-or 4-loculed, 1--1.7 mm. Pistillate flowers in proximal axils, 1.5--4 mm; styles 0.3--1.5 mm; stigmas 4-lobed. Seeds not recurved, yellowish white with purple tinge, fusiform, 1.2--3.8 ´ 0.4--0.8 mm, apex with style situated at center; testa dull, 3 cell layers thick, pitted; aeroleareoles regularly arranged in 20--60 longitudinal rows, not ladderlike, 4--6-angled, longer than broad, end walls not raised. 2n = 12, 36, 42, 48, 54, 60.
Monoecious; stems profusely branched, 1–8 dm; lvs 0.5–3 cm × 0.2–2 mm, spreading, not so sharply pointed as in our other spp., with sloping shoulders at the base, minutely serrulate with 20–100 unicellular teeth per side; anthers dithecal, with 4 microsporangia; style apical; seeds 1.2–2.5 mm, purple-tinged, fusiform, pitted, the areolae 4–6-angled, about as long (0.08–0.1 mm) as wide, in 20–40 rows; 2n=12, 36, 48, 54, 60. Widespread in N. and S. Amer., n. to Me., s. Que., Man., Alta., and Wash. The widespread var. guadalupensis, slender, with stems 0.2–1 mm thick, and with 50–100 teeth on each side of the lf, tends to give way at the n. to var. olivacea (Rosend. & Butters) R. R. Haynes, which occurs from N.Y. and s. Que. to n. Ind., n. Io., and s. Man., and is stouter, with stems mostly 1–2 mm thick, and with 20–40 teeth per side of the lf. (N. olivacea)
Life form annual
Growth form herb
Growth support aquatic
Foliage retention -
Sexuality monoecy
Pollination -
Spread -
Mature width (meter) -
Mature height (meter) 0.3
Root system -
Rooting depth (meter) 0.1
Root diameter (meter) -
Flower color
Blooming months
JanFebMar
AprMayJun
JulAugSep
OctNovDec
Fruit color
Fruiting months -
Nitrogen fixer -
Photosynthetic pathway c3

Environment

Light 7-8
Soil humidity 8-8
Soil texture -
Soil acidity 3-9
Soil nutriment -
Hardiness (USDA) 4-12

Usage

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

Cultivation

Mode -
Germination duration (days) -
Germination temperacture (C°) -
Germination luminosity -
Germination treatment -
Minimum temperature (C°) -
Optimum temperature (C°) -
Size -
Vigor -
Productivity -

Images

Najas guadalupensis unspecified picture

Distribution

Najas guadalupensis world distribution map, present in Aruba, Åland Islands, Bahamas, Bolivia (Plurinational State of), Brazil, Colombia, Costa Rica, Cuba, Czech Republic, Dominica, Ecuador, Micronesia (Federated States of), Georgia, Guatemala, Honduras, Haiti, Hungary, Jamaica, Japan, Malaysia, Nicaragua, Panama, Peru, Palau, Puerto Rico, Uruguay, United States of America, and Venezuela (Bolivarian Republic of)

Conservation status

Najas guadalupensis threat status: Least Concern

Identifiers

LSID urn:lsid:ipni.org:names:166929-2
WFO ID wfo-0000769498
COL ID 45KZD
BDTFX ID -
INPN ID 630212
Wikipedia (EN) Link
Wikipedia (FR)

Synonyms

Najas guadalupensis Caulinia guadalupensis Najas microdon Najas microdon var. guadalupensis Najas flexilis var. guadelupensis Najas microdon var. curassavica Najas guadalupensis var. guadalupensis

Lower taxons

Najas guadalupensis subsp. floridana Najas guadalupensis subsp. muenscheri Najas guadalupensis subsp. olivacea Najas guadalupensis subsp. guadalupensis