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Davis' knotweed, Newberry's fleeceflower, Newberry's knotweed

fleeceflower

Habit Plants 12–42(–50) cm. Herbs, perennial; roots woody.
Stems

ascending to erect, glabrous or pubescent.

ascending to erect, glabrous or pubescent to pilose or tomentose.

Leaves

ocrea reddish brown, funnelform, 0.3–3 cm, margins oblique, glabrous or finely pubescent to pilose;

petiole 0.3–10(–15) mm;

blade oblong-ovate to ovate, rarely broadly lanceolate, 2.1–7.5(–9.5) × 1.1–5 cm, subcoriaceous, base truncate or, rarely, cordate, margins entire, glabrous or ciliate, apex obtuse to acute, faces often glaucous, glabrous or pubescent.

deciduous, mostly cauline, alternate, petiolate or sessile;

ocrea persistent or deciduous, chartaceous;

blade narrowly lanceolate to ovate, margins entire, sometimes irregularly undulate.

Inflorescences

axillary, racemelike;

peduncle essentially absent.

terminal, subterminal, or axillary, racemelike or paniclelike;

peduncle present or essentially absent.

Pedicels

0.5–1.9(–2.4) mm.

present.

Flowers

1–4 per ocreate fascicle, rarely some flowers with stamens poorly developed;

perianth greenish to pinkish white, 2–4.5 mm;

tepals slightly dimorphic or, rarely, distinctly so, oblong-ovate to obovate, apex obtuse;

anthers yellow or pink.

bisexual, 1–5 per ocreate fascicle, base stipelike or not;

perianth nonaccrescent, creamy or greenish to yellowish white or pink, rotate, glabrous;

tepals 5, connate ca. 1/4 their length, petaloid, slightly to distinctly dimorphic, outer 2 smaller than inner 3;

stamens 8;

filaments distinct, free or adnate to perianth tube, glabrous;

anthers yellow to pink or reddish purple, ovate to elliptic;

styles 3, erect or spreading, distinct or connate proximally;

stigmas capitate.

Achenes

exserted, yellowish brown, not beaked distally, 3.2–6(–8.3) × 2.1–5 mm, shiny, faces not concave.

includedor exserted, yellowish or dark brown, unwinged, 3-gonous, glabrous.

Seeds

embryo usually curved.

x

= 8, 10, 11.

2n

= 20.

Aconogonon davisiae

Aconogonon

Distribution
from FNA
CA; ID; OR; WA
[WildflowerSearch map]
[BONAP county map]
w North America; Europe; Asia
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

The varieties are largely sympatric and often intergrade. The treatment here follows Hong S. P. (1991).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species ca. 25 (3 in the flora).

The orthography of and author citation for the genus name have been matters of confusion. Meisner published the taxon as Polygonum sect. Aconogonon. Reichenbach elevated it to generic rank and changed the orthography, apparently deliberately, to Aconogonum. Debate centers on whether Reichenbach’s name is new (Aconogonum Reichenbach) or should be treated as Meisner’s section name elevated to generic rank [Aconogonon (Meisner) Reichenbach]. Following established custom, we here use Aconogonon.

Aconogonon often is treated as a section of Persicaria (L.-P. Ronse Decraene and J. R. Akeroyd 1988); pollen morphology, inflorescence type, and seed and stem anatomy have been used by some taxonomists for segregation at the generic level (K. Haraldson 1978; Hong S. P. 1991).

Aconogonon campanulatum (Hooker f.) H. Hara is planted as an ornamental. C. L. Hitchcock and A. Cronquist (1973) reported it as escaping and probably established west of the Cascade Mountains, especially in Seattle, Washington. P. Zika (pers. comm.) searched numerous herbaria in the Pacific Northwest. He found no voucher indicating that A. campanulatum has escaped there, although it is cultivated occasionally in the Seattle area; it therefore is excluded here.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Faces of leaf blades pubescent, rarely glabrescent
var. davisiae
1. Faces of leaf blades glabrous
var. glabrum
1. Inflorescences axillary, racemelike; plants 12-42(-50) cm; leaf blades oblong-ovate to ovate, rarely broadly lanceolate, 2.1-7.5(-9.7) × 1.1-5 cm, often glaucous
A. davisiae
1. Inflorescences usually terminal or subterminal, sometimes also axillary, paniclelike; plants (30-)50-150(-200) cm; leaf blades narrowly lanceolate to ovate, 5-20 × 1.4-8 cm, not glaucous
→ 2
2. Achenes 2.6-3.8 mm, included or exserted, tan to grayish, faces usually not concave; inflorescences terminal, sometimes also axillary; Alaska, n Yukon, nw Northwest Territories
A. alaskanum
2. Achenes (3-)3.8-7 mm, usually exserted, yellowish brown, faces concave; inflorescences usually terminal, subterminal, and axillary; n California, Oregon, Washington, Idaho, w Montana, n Nevada
A. phytolaccifolium
Source FNA vol. 5, p. 599. FNA vol. 5, p. 597. Authors: Harold R. Hinds†, Craig C. Freeman.
Parent taxa Polygonaceae > subfam. Polygonoideae > Aconogonon Polygonaceae > subfam. Polygonoideae
Sibling taxa
A. alaskanum, A. phytolaccifolium
Subordinate taxa
A. davisiae var. davisiae, A. davisiae var. glabrum
A. alaskanum, A. davisiae, A. phytolaccifolium
Synonyms Polygonum davisiae, A. newberryi, Polygonum newberryi Polygonum section A.
Name authority (W. H. Brewer ex A. Gray) Soják: Preslia 46: 151. (1974) unknown: Handb. Nat. Pfl.-Syst., 236. (1837)
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