Amaranthus watsonii

Standley

Bull. Torrey Bot. Club 41: 505. 1914.

Common names: Watson’s amaranth
Treatment appears in FNA Volume 4. Treatment on page 418. Mentioned on page 412, 413.

Plants pubescent and glandular-pubescent, especially on bracts. Stems ascending to erect, usually much-branched, 0.1–1 m; branches usually ascending. Leaves: petiole shorter than or equaling blade; blade ovate, obovate to elliptic, or oblongelliptic, 1–8 × 0.5–4 cm, base broadly cuneate to nearly rounded, margins entire, plane or slightly undulate, apex obtuse to emarginate, usually with terminal mucro. Inflorescences mostly terminal, erect spikes to panicles, usually thick and uninterrupted, with few axillary clusters in basal part of plant. Bracts: of pistillate flowers with long-excurrent midrib, 3–4 mm, longer than tepals, apex long-acuminate or mucronulate; of staminate flowers 2.5–4 mm, usually equaling outer tepals, apex long-acuminate or mucronulate. Pistillate flowers: tepals with dark midribs not excurrent, spatulate to fan-shaped, 1.7–2.2 mm, apex obtuse, with terminal mucro; style-branches spreading; stigmas 2 (–3). Staminate flowers: tepals 5, equal or subequal, 1.5–2 (–3) mm, apex acute or almost obtuse; inner tepal apex acuminate or mucronulate; stamens 3–5. Utricles light-brown to brown, obovoid to subglobose, 1.5–2 mm, shorter than tepals, walls thin, smooth or indistinctly rugose. Seeds dark reddish-brown to nearly black, (0.8–) 1–1.2 mm diam., shiny.


Phenology: Flowering late winter–spring, summer–fall.
Habitat: Coastal dunes, beaches, sandy inland areas, weakly saline flats
Elevation: 0-100 m

Distribution

Ariz., Calif., Mexico (Baja California), Mexico (Baja California Sur), Mexico (Sonora), Europe (reported as rare), Europe (non-naturalized casual alien)

Discussion

Selected References

None.

Lower Taxa

None.

"thick" is not a number.

... more about "Amaranthus watsonii"
obtuse;acute;obtuse;mucronulate;long-acuminate;mucronulate;long-acuminate;obtuse;emarginate +
Sergei L. Mosyakin +  and Kenneth R. Robertson +
Standley +
broadly cuneate +  and nearly rounded +
Undefined subg. Acnida +
1 cm10 mm <br />0.01 m <br /> (8 cm80 mm <br />0.08 m <br />) +
obovate +  and elliptic or oblongelliptic +
0.5 cm5 mm <br />0.005 m <br /> (4 cm40 mm <br />0.04 m <br />) +
persistent +
narrowly lanceolate +  and subulate-linear +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
Watson’s amaranth +
Ariz. +, Calif. +, Mexico (Baja California) +, Mexico (Baja California Sur) +, Mexico (Sonora) +, Europe (reported as rare) +  and Europe (non-naturalized casual alien) +
0-100 m +
peripheral +
staminate +  and pistillate +
not enfolding +
minute +  and small +
not +  and dehiscent +
Coastal dunes, beaches, sandy inland areas, weakly saline flats +
terminal +  and axillary +
reduced +
undulate +, plane +  and entire +
not excurrent +  and long-excurrent +
scarious +  and membranaceous +
well-developed +
Flowering late winter–spring, summer–fall. +
rudimentary +
Bull. Torrey Bot. Club +
dark reddish-brown +  and nearly black +
1mm;1.2mm +
lenticular +  and subglobose +
uninterrupted +
well-developed +
much-branched +
prostrate +  and decumbent +
ascending +  and erect +
10 cm100 mm <br />0.1 m <br /> (100 cm1,000 mm <br />1 m <br />) +
not fleshy +
slender +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Acanthochiton +, Acnida +, Albersia +, Amblogyna +, Euxolus +, Mengea +, Sarratia +  and Scleropus +
Amaranthus watsonii +
Amaranthus sect. Saueranthus +
species +
mucronulate +  and acuminate +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
distinct +
spatulate +  and fan-shaped +
subequal +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
indurate +, membranaceous +, chartaceous +  and scarious +
walled +  and 3(-5)-veined +
light-brown +  and brown +
circumscissile +
tuberculate +  and rugose +
obovoid +  and subglobose +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
membranaceous +
Rugose (?) +  and Smooth (?) +
glandular-pubescent +  and pubescent +