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dwarf spiraea, shinyleaf meadowsweet

bridewort, willowleaf meadowsweet

Habit Shrubs, 3–10(–15) dm. Shrubs, 10–20 dm, thicket forming.
Stems

erect to arching, branched.

erect to ascending or spreading, rarely branched.

Leaves

petiole 3–8 mm, sparsely hairy;

blade ovate to elliptic or suborbiculate, 2–10 × 1–2.5 cm, coriaceous, base obtuse, rounded, or subcordate, margins irregularly, coarsely and sharply doubly serrate from midpoint to apex, teeth acute and mucronate, number of primary and secondary serrations 1 times number of secondary veins (excluding inter-secondary veins), venation pinnate cladodromous, secondary veins not prominent, apex acute, obtuse, or rounded, abaxial surface mostly glabrous, adaxial glabrous.

petiole 2–6 mm;

blade narrowly rhombic to rhombic or lanceolate to narrowly elliptic, usually widest at middle, 3–7 × 1–3 cm, length 3–5 times width, chartaceous, base acute, margins sharply serrate to serrulate nearly to base, number of primary and secondary serrations 1 times number of secondary veins (excluding inter-secondary veins), venation pinnate craspedodromous, secondary veins not prominent, regularly terminating in primary teeth, inter-secondary veins usually 1–4 per leaf, apex acute, abaxial surface mostly puberulent, adaxial glabrous.

Inflorescences

mostly terminal, corymbiform, 2–5 × 3–10 cm height 0.4–1.1 times diam.;

branches rarely in axils of leaves, glabrous or glabrate.

mostly terminal, cylindric to obconic panicles, 5–10 × 2–4 cm height 2–5 times diam.;

branches sometimes in axils of leaves, puberulent or glabrous.

Pedicels

1–3 mm, glabrous or glabrate.

3–6 mm, puberulent or glabrous.

Flowers

4–7 mm diam.;

hypanthia hemispheric, 0.8–1 mm, abaxial surface glabrous or pubescent, adaxial glabrous;

sepals triangular, 0.5–1 mm;

petals chalky white to pink, orbiculate, 1.3–1.5 mm;

staminodes 5–15 reduced to serrations;

stamens 15–20, 2 times petal length.

4–7(–10) mm diam.;

hypanthia hemispheric, 0.8–1 mm, abaxial surface glabrous or sparsely puberulent, adaxial glabrous;

sepals ovate, 0.8–1 mm;

petals pink, elliptic to widely obovate, 1.8–2 mm;

staminodes 0;

stamens 28–32, 2 times petal length.

Follicles

nearly fusiform, 2–3 mm, shiny, glabrous.

oblanceoloid, 4 mm, glabrous, adaxial suture glabrous or ciliate.

2n

= 36.

Spiraea corymbosa

Spiraea salicifolia

Phenology Flowering May–Oct; fruiting Jun–Nov. Flowering Jun–Aug; fruiting Jun–Sep.
Habitat Open rocky soil, rocky, lightly wooded sites, dry or fast draining slopes, rocky edges of woods Old homesteads in moist areas, flood plains
Elevation 0–500 m (0–1600 ft) 0–300 m (0–1000 ft)
Distribution
from FNA
GA; MA; MD; NC; NJ; PA; TN; VA; WV; NS; ON [Introduced in e Europe]
from FNA
GA; KY; MI; MS; NC; VA; VT; ON; e Europe; e Asia [Introduced in North America; introduced also in w, c Europe]
[BONAP county map]
Discussion

H. A. Gleason and A. Cronquist (1963) and L. J. Uttal (1974) considered Spiraea corymbosa to be a variety of S. betulifolia. K. Sax (1936) found S. corymbosa to be a triploid with complete pollen sterility and hypothesized that it must exist as a diploid, or form viable egg cells, because it is involved in hybrids. If so, these cytological differences may be correlated with some morphological variation.

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

Spiraea salicifolia is escaped from cultivation in northeastern North America. K. Sax (1936) reported a specimen of S. salicifolia as tetraploid; it is possible that it was not a European specimen, so this count may be unreliable.

The name Spiraea salicifolia is often misapplied to individuals of S. alba var. alba or S. alba var. latifolia (see discussion above). In addition, being a cultivated species that has been popular in gardens and likely introduced and escaped in various hybridized forms, the intermediates and potential hybrids with native taxa can make identification difficult. For problematic specimens that appear to be hybrids, see A. J. Silverside (1988, 1990).

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

Source FNA vol. 9, p. 403. FNA vol. 9, p. 402.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Spiraeeae > Spiraea Rosaceae > subfam. Amygdaloideae > tribe Spiraeeae > Spiraea
Sibling taxa
S. alba, S. cantoniensis, S. chamaedryfolia, S. douglasii, S. japonica, S. lucida, S. prunifolia, S. salicifolia, S. splendens, S. stevenii, S. thunbergii, S. tomentosa, S. virginiana, S. ×hitchcockii, S. ×pyramidata, S. ×vanhouttei
S. alba, S. cantoniensis, S. chamaedryfolia, S. corymbosa, S. douglasii, S. japonica, S. lucida, S. prunifolia, S. splendens, S. stevenii, S. thunbergii, S. tomentosa, S. virginiana, S. ×hitchcockii, S. ×pyramidata, S. ×vanhouttei
Synonyms S. betulifolia var. corymbosa, S. ostryfolia, S. repens, S. sororia S. amena
Name authority Rafinesque: Précis Découv. Somiol., 36. (1814) Linnaeus: Sp. Pl. 1: 489. (1753)
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