Najas guadalupensis (Spreng.) Magnus
Family: Hydrocharitaceae
Guadalupe Waternymph,  more...
[Najas flexilis var. fusiformis ]
Najas guadalupensis image
Sue Carnahan  
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. By having unicellular teeth on the leaf margin, Najas guadalupensis resembles N. flexilis and N. graminea. The seeds of N. guadalupensis are pitted; those of N. flexilis are smooth. The sheaths of N. guadalupensis are rounded to slightly auriculate; those of N. graminea are deeply auriculate.

Annual submersed aquatic herb to 0.9 m long Leaves: opposite, stalkless, 0.3 - 3.3 cm long, 0.2 - 2 mm wide, widening to a 1 - 3.4 mm sheath at base, linear with a rounded to abruptly pointed tip, with 20 to 100 tiny teeth per side (may require hand lens). Flowers: either male or female, found on the same plant (monoecious), borne one to three in leaf axils, green, tiny. The 1.5 - 3 mm long male flowers have four-lobed beaks, and the 1.5 - 4 mm long female flowers have four-lobed stigmas and stout styles. Fruit: achene-like, yellowish white with a hint of purple, 1.2 - 3.8 mm long, 0.4 - 0.8 mm wide, spindle-shaped (fusiform), dull, pitted in ten to 60 rows. Stems: slender, highly branched, 11 cm - 0.9 m long, 0.1 - 2 mm wide, rooting at the nodes.

Similar species: Najas flexilis and Najas guadalupensis both have finely toothed leaves that can usually only be seen using a hand lens. Najas flexilis differs by having glossy seeds and leaves that taper to a narrow pointed tip. Najas guadalupensis ssp. guadalupensis is distinguished from other subspecies by having a style shorter than 0.5 mm and seeds with only ten to twenty rows of pits.

Flowering: September

Habitat and ecology: Occasional in shallow water of ponds and lakes.

Occurence in the Chicago region: native

Etymology: Najas comes from the Greek name for a river nymph, naias. Guadalupensis means "from Guadalupe Island, Mexico."

Author: The Morton Arboretum

Monoecious; stems profusely branched, 1-8 dm; lvs 0.5-3 cm נ0.2-2 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)

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
FNA 2000, Jepson 2012
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Herbaceous, aquatic annuals, stems very slender and thread-like, to 90 cm long and 0.1-2 mm wide, the internodes 0.1-9 cm long, submerged or floating and often profusely branched distally, the surfaces without prickles, green to tan or dark brown in color. Leaves: Linear and thread-like, spreading and lax with age, 0.3-3.3 cm long and 0.2-2.1 mm wide, margins minutely serrulate, with 18-100 teeth per side, the midveins without prickles abaxially, apices rounded to truncate and slightly auriculate with 1-3 teeth, the teeth unicellular, the blades with sheaths 1-3.4 mm wide. Flowers: Generally 1-3 per axil, with staminate and pistillate flowers on same plants; staminate flowers 1.5-3 mm long, with 4-lobed involucral beaks, these 0.2-1.3 mm long, anthers 1- or 4-loculed, pistillate flowers 1-1.7 mm long, 1.5-4 mm long, styles 0.3-1.5 mm long, stigmas 4-lobed, staminate flowers borne in distal axils, pistillate flowers borne in proximal axils. Fruits: Seeds yellowish white with a purple tinge, fusiform, 1.2-3.8 mm long and 0.4-0.8 mm wide, not recurved, apices with styles situated at the center, the testa dull, 3 cell layers thick, pitted, areoles regularly arranged in 20-60 longitudinal rows, not ladd Ecology: Found from 4,000-6,000 ft (1219-1829 m); flowering August-October Distribution: Widespread throughout the United States. Ethnobotany: Unknown. Etymology: Najas comes from the Greek Naias, a water nymph, and guadalupensis means of or from Guadalupe Mountain. Synonyms: Numerous, see Tropicos Editor: LCrumbacher2012
Najas guadalupensis image
Sue Carnahan  
Najas guadalupensis image
Sue Carnahan  
Najas guadalupensis image
Sue Carnahan  
Najas guadalupensis image
Sue Carnahan  
Najas guadalupensis image
Sue Carnahan  
Najas guadalupensis image
Najas guadalupensis image
Garrett E. Crow  
Najas guadalupensis image
Garrett E. Crow  
Najas guadalupensis image
Garrett E. Crow  
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Zoya Akulova  
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