Spiraea corymbosa |
Spiraea ×vanhouttei |
|
---|---|---|
dwarf spiraea, shinyleaf meadowsweet |
bridal-wreath, spirea |
|
Habit | Shrubs, 3–10(–15) dm. | Shrubs, 10–20(–25) dm, not rhizomatous. |
Stems | erect to arching, branched. |
arching, virgate, 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 2–7 mm; blade ovate or rhombic-ovate to obovate, 3–5 × 2–3 cm, membranous, base cuneate to obtuse, margins crenate to coarsely serrate on distal 1/2–3/4, irregularly doubly serrate, or, sometimes, 3–5 lobed (especially long shoot leaves), venation suprabasal actinodromous, secondary veins not prominent, apex acute, surfaces 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 axillary (borne profusely along branches), corymbiform or hemispheric panicles, 3–6 × 3–6 cm; branches glabrous. |
Pedicels | 1–3 mm, glabrous or glabrate. |
5–10 mm, 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. |
7–10 mm diam.; hypanthia campanulate, 1–1.5 mm, surfaces glabrous; sepals triangular, 1–1.5 mm; petals white to cream, orbiculate, 2–3 mm; staminodes 10–16, mostly distinct; stamens 20–25, 0.5 times petal length. |
Follicles | nearly fusiform, 2–3 mm, shiny, glabrous. |
falcate, 2–3 mm, glabrous. |
2n | = 36. |
|
Spiraea corymbosa |
Spiraea ×vanhouttei |
|
Phenology | Flowering May–Oct; fruiting Jun–Nov. | Flowering May–Jun; fruiting Jun–Oct. |
Habitat | Open rocky soil, rocky, lightly wooded sites, dry or fast draining slopes, rocky edges of woods | Old homesteads, pastures, roadsides, railways |
Elevation | 0–500 m (0–1600 ft) | 0–2000 m (0–6600 ft) |
Distribution |
GA; MA; MD; NC; NJ; PA; TN; VA; WV; NS; ON [Introduced in e Europe] |
AR; CO; CT; IL; KY; LA; MA; MD; MI; MN; MO; MT; NC; NE; NM; NY; OH; PA; UT; VA; WA; WV; NS; ON; Asia (China) [Introduced in North America; introduced also in Europe] |
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 ×vanhouttei is widely planted as an ornamental near homes and along broadways. Concerning the potential for threat as an invasive or weedy species, R. B. Kaul (pers. comm.) has observed that it may persist for decades in old hedges and ornamental plantings; he has not seen any evidence of it volunteering or naturalizing and, despite repeated searches, has never seen a seed or seedling. J. A. Harris (1917) questioned whether Spiraea ×vanhouttei had been proven to be the hybrid S. cantoniensis and S. trilobata. C. Sterling (1966) described the carpel anatomy of S. ×vanhouttei; but he did not examine the postulated parents. M. De Cleene and J. De Ley (1981) attempted to define the host range of infectious hairy-root (Agrobacterium rhizogenes) and correlate hosts with taxonomic relationships; they verified that S. prunifolia and S. ×vanhouttei are hosts to this disease but did not test other species of the genus. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 403. | FNA vol. 9, p. 410. |
Parent taxa | Rosaceae > subfam. Amygdaloideae > tribe Spiraeeae > Spiraea | Rosaceae > subfam. Amygdaloideae > tribe Spiraeeae > Spiraea |
Sibling taxa | ||
Synonyms | S. betulifolia var. corymbosa, S. ostryfolia, S. repens, S. sororia | S. aquilegiifolia var. vanhouttei |
Name authority | Rafinesque: Précis Découv. Somiol., 36. (1814) | Spiraea ×vanhouttei (Briot) Carrière: Rev. Hort. 48: 260. (1876) |
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