Echinodorus tenellus

(Martius) Buchenau

Index Crit. Butom. Alism. Juncagin. 21. 1868.

Basionym: Alisma tenellum Martius in J. J. Roemer and J. A. Schultes, Syst. Veg. 7(2): 1600. 1830
Synonyms: Echinodorus parvulus Engelmann Echinodorus tenellus var. parvulus (Engelmann) Fassett Helianthium parvulum
Treatment appears in FNA Volume 22.

Herbs, annual, relatively slender, to 25 cm; rhizomes absent. Leaves: submersed leaves mostly present, sessile; emersed leaves with petioles 4–5-ridged, 1.2–9.5 cm; blade with translucent markings absent, linear, 1–7.4 × 0.2–0.5 cm, base attenuate; if emersed, narrowly lanceolate to ovate. Inflorescences umbels, rarely racemes, of 1–2 whorls, each 4–6-flowered, erect, to 6 × 8 cm, not proliferating; peduncles terete, 1.2–4 cm; rachis absent or if present, terete; bracts connate ca. ½ length, deltate, 2.8–4.9 mm, coarse, margins delicate; pedicels spreading, 0.5–3 cm. Flowers 6–8 mm wide; sepals slightly appressed, 3–5-veined, veins not papillate; petals clawed; stamens 9; anthers basifixed; pistils 15–20. Fruits obovate, flattened, 0–3-ribbed, not abaxially keeled, 0.8–1.5 × 0.8–1 mm, glands absent; beak lateral, 0.1–0.2 mm. Chromosome number unknown.


Phenology: Flowering summer–fall.
Habitat: Sandy soil along margins of small streams or lakes
Elevation: 0–1500 m

Distribution

V22 403-distribution-map.jpg

Ala., Conn., Fla., Ga., Ill., Kans., Mass., Mich., N.Y., S.C., Tex., Vt., se Mexico, West Indies, Central America (Guatemala), Central America (Nicaragua), South America

Discussion

Echinodorus tenellus has often been separated into two species, one in North America and the other in the tropics. Whenever Echinodorus is studied throughout the range, differences between the two species break down, and a continuum exists from one species to the next. We recognize that overlap; therefore we are combining E. parvulus with E. tenellus.

Selected References

None.

Lower Taxa

None.
... more about "Echinodorus tenellus"
Obtuse (?) +  and Acute (?) +
Robert R. Haynes +  and C. Barre Hellquist +
(Martius) Buchenau +
attenuate +
Alisma tenellum +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
1 cm10 mm <br />0.01 m <br /> (7.4 cm74 mm <br />0.074 m <br />) +
linear +  and lanceolate +
0.2cm +  and 0.5cm +
shorter than to longer than pedicels +
deltate +
Ala. +, Conn. +, Fla. +, Ga. +, Ill. +, Kans. +, Mass. +, Mich. +, N.Y. +, S.C. +, Tex. +, Vt. +, se Mexico +, West Indies +, Central America (Guatemala) +, Central America (Nicaragua) +  and South America +
0–1500 m +
u--shaped +
subsessile +  and pedicellate +
hypogynous +
0.8mm;1.5mm +
keeled +, flattened +  and obovate +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Sandy soil along margins of small streams or lakes +
decumbent +  and floating +
decumbent +  and erect +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
0 cm0 mm <br />0 m <br /> (8 cm80 mm <br />0.08 m <br />) +
narrowly lanceolate;ovate +
1.2 cm12 mm <br />0.012 m <br /> (9.5 cm95 mm <br />0.095 m <br />) +
decumbent +  and floating +
decumbent +  and erect +
0.5 cm5 mm <br />0.005 m <br /> (3 cm30 mm <br />0.03 m <br />) +
1.2 cm12 mm <br />0.012 m <br /> (4 cm40 mm <br />0.04 m <br />) +
deciduous +
4-5-ridged +
Flowering summer–fall. +
Index Crit. Butom. Alism. Juncagin. +
decumbent +  and floating +
decumbent +  and erect +
if present +
not septate +
persistent +
recurved;spreading +
herbaceous;leathery +
lateral +  and terminal +
papillose +  and smooth +
Echinodorus parvulus +, Echinodorus tenellus var. parvulus +  and Helianthium parvulum +
Echinodorus tenellus +
Echinodorus +
species +
not papillate +
submersed +  and emersed +
glabrous +  and stellate-pubescent +
bracteolate +  and branching +