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dwarf spiraea, shinyleaf meadowsweet

mountain spiraea, rose meadowsweet, rosy spiraea, subalpine spiraea, subalpine spirea

Habit Shrubs, 3–10(–15) dm. Shrubs, 2–10 dm.
Stems

erect to arching, branched.

spreading to ascending, 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 1–4 mm;

blade ovate to elliptic, 1–4 × 1–2(–3) cm, chartaceous, base usually obtuse, sometimes acute, margins crenate to serrate distally from middle, venation pinnate craspedodromous, secondary veins prominent, apex usually obtuse, sometimes acute, abaxial surface glabrous or 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, corymbiform or hemispheric panicles, 100–1000+-flowered, 2–4 × 2–4 cm height 0.8–1 times diam.;

branches glabrous or puberulent.

Pedicels

1–3 mm, glabrous or glabrate.

1–3(–5) mm, glabrous or puberulent.

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.

2–4 mm diam.;

hypanthia hemispheric, 0.5–1.1 mm, abaxial surface glabrous or pubescent, adaxial pubescent;

sepals triangular, 0.8–1 mm;

petals light to dark pink, ovate to obovate, 1–2.5 mm, veins prominent;

staminodes 5–10, reduced, fused, appearing as scalloped ring;

stamens 35–40, 2 times petal length.

Follicles

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

oblanceoloid, 2–3 mm, shiny, glabrous, adaxial suture sparsely ciliate.

2n

= 36.

Spiraea corymbosa

Spiraea splendens

Phenology Flowering May–Oct; fruiting Jun–Nov.
Habitat Open rocky soil, rocky, lightly wooded sites, dry or fast draining slopes, rocky edges of woods
Elevation 0–500 m (0–1600 ft)
Distribution
from FNA
GA; MA; MD; NC; NJ; PA; TN; VA; WV; NS; ON [Introduced in e Europe]
from FNA
CA; ID; MT; OR; WA; WY; AB; BC
[WildflowerSearch map]
[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.)

Varieties 2 (2 in the flora).

The name Spiraea densiflora Nuttall ex Rydberg subsp. splendens (É. N. Baumann ex K. Koch) Abrams, which pertains here, is incorrect in relation to the priority of S. splendens (1875) over S. densiflora, which is an illegitimate name with no priority.

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

Key
1. Young stems, leaf abaxial surfaces, and pedicels and bracteoles glabrous or glabrate.
var. splendens
1. Young stems, leaf abaxial surfaces, and pedicels and bracteoles puberulent.
var. rosea
Source FNA vol. 9, p. 403. FNA vol. 9, p. 405.
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. salicifolia, S. stevenii, S. thunbergii, S. tomentosa, S. virginiana, S. ×hitchcockii, S. ×pyramidata, S. ×vanhouttei
Subordinate taxa
S. splendens var. rosea, S. splendens var. splendens
Synonyms S. betulifolia var. corymbosa, S. ostryfolia, S. repens, S. sororia
Name authority Rafinesque: Précis Découv. Somiol., 36. (1814) E. N. Baumann ex K. Koch: Monatsschr. Vereines Beförd. Gartenbaues Königl. Preuss. Staaten 18: 294. (1875)
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