Spiraea L.

3. Spiraea L. View in CoL 2

Deciduous shrubs. Leaves simple, rarely lobed, entire or serrate, usually shortly petiolate, exstipulate. Inflorescence paniculate, corymbose or umbellate. Petals white or pink; stamens 15 to numerous; carpels 5, free. Follicles dehiscent along the ventral suture. Seeds several.

In addition to the naturalized species described below, many species and hybrids are cultivated for ornament in gardens.

Literature: H. Zabel, Die strauchigen Spiräen unserer Gärten. Berlin. 1893. V. V. Shulgina, Derev’ja i Kustarniki SSSR 3: 269- 332 (1954). G. Krüssmann, Handbuch der Laubholzkunde 2 ’. 489- 499. Berlin. 1962. 1 Inflorescence a panicle or compound corymb, terminating a long shoot

2 Inflorescence a panicle, longer than wide 3 Sepals erect in fruit; nectar-ring distinct

4 Panicles cylindrical; flowers usually pink 1. salicifolia

4 Panicles conical; flowers usually white 2. alba

3 Sepals deflexed in fruit; nectar-ring absent

5 Follicles glabrous 3. douglasii

5 Follicles pubescent 4. tomentosa

2 Inflorescence a compound corymb, at least as wide as long 6 Stamens equalling or shorter than petals 5. decumbens

6 Stamens at least 1-5 times as long as petals

7 Leaves acute; petals pink 6. japonica

7 Leaves obtuse; petals white or yellowish-white 7. corymbosa Inflorescence a simple umbel or corymb, terminating a short shoot Inflorescence sessile or the lower very shortly pedunculate

13. hypericifolia

Inflorescence pedunculate

9 Leaves with 3 longitudinal veins 10 Veins conspicuous; petals shorter than stamens 11. crenata

10 Veins inconspicuous; petals longer than stamens

12. x vanhouttei

9 Leaves pinnately veined 11 Branches angular; petals c. 6 mm 8. chamaedryfolia

11 Branches terete; petals 2-3 mm

12 Leaves of non-flowering shoots serrate towards apex,

glabrous at maturity 9. media

12 Leaves of non-flowering shoots entire, tomentose beneath

10. cana Subgen. Spiraea. Inflorescence a terminal panicle or compound corymb, terminating a long shoot.