Spiraea L. (Rosaceae)

In North Carolina, Spiraea is represented by thirteen species, eight of which are exotics. The only species currently federally listed is Spiraea virginiana (Fed T). Spiraea corymbosa is state listed (State E). Note that, as for Liatris and Geum, the majority of rare taxa are found in the Piedmont and mountains.

Federally listed taxon—
Spiraea virginiana (Fed T, State T | S2 G2)

Habitat. Flood-scoured, rocky river banks in the Ohio River drainage.

Range. Endemic to eastern North America.

Additional resources. NHP | Recovery plan

Key to Spiraea in North Carolina

Key adapted from Weakley (2010). Photos by Krings, unless otherwise indicated. Line drawings from Britton & Brown (1913). Maps courtesy of USDA PLANTS and the North Carolina Natural Heritage Program.

1. Inflorescence a simple umbel; plants flowering early to mid-spring (Mar–Apr)...2. [exotic]

2. Flowers 10–15 mm in diam...3.

3. Leaves 2–7 cm long, unlobed or sometimes slightly 3-lobed, margins coarsely serrate; inflorescences with > 6 flowers; calyx lobes acute...S. cantoniensis

3'. Leaves 1–4 (–5) cm long, unlobed, margins finely serrulate; inflorescences with 3–6 flowers; calyx lobes obtuse to rounded...S. prunifolia

2'. Flowers 6–10 mm in diam...4.

4. Leaf blades linear to lanceolate, 2.5–4 cm x 0.3–1 cm, > 4x as long as wide; flowers 6–8 mm in diameter...S. thunbergii

4'. Leaf blades ovate to obovate, 3–5 cm x 2–3 cm, < 2x as long as wide; flowers 7–10 mm in diameter...S. x vanhouttei

1'. Inflorescence a compound corymb or panicle; plants mostly flowering in summer, sometimes to fall (Jun–Sep)...5. [native or exotic]

5. Inflorescence a corymb, broader than long...6.

6. Leaf apex rounded or obtuse (sometimes some leaves acute in S. virginiana); petals white (rarely pink); native...7.

7. Leaves 1–2 x as long as wide, apex rounded to obtuse, base rounded to broadly cuneate; follicle 2–3 mm long...S. corymbosa

7'. Leaves 2–4 x as long as wide, apex obtuse (sometimes some leaves acute), base narrowly cuneate to attenuate; follicles 1–2 mm long...S. virginiana*

6'. Leaf apex acute to long acuminate; petals pink (rarely white or red); exotic...8.

8. Leaves pubescent beneath...S. japonica var. fortunei

8'. Leaves glabrous beneath...Spiraea x bumalda

5'. Inflorescence a panicle, longer than wide...9.

9. Lower leaf surface densely tomentose, the tomentum obscuring the surface...10.

10. Follicles pubescent; common in boggy wetlands...S. tomentosa

10'. Follicles glabrous; rare introduction...S. x billiardii

9'. Lower leaf surface glabrous or with a few scattered hairs that do not obscure the surface...11.

11. Leaves widest below the middle, lanceolate to oblong-lanceolate...S. salicifolia

11'. Leaves widest above the middle, oblanceolate to obovate or oblong...12.

12. Leaves finely and sharply toothed; inflorescence and hypanthium pubescent;
sepals usually obtuse...S. alba

12'. Leaves coarsely and bluntly toothed; inflorescence and hypanthium usually glabrous;
sepals usually acute...S. latifolia