SPIR.EA 



SPIILEA 



3207 



SPIRAEA (ancient Greek name of a plant used for 

 garlands, derived from speira, band, wreath; probably 

 first used for the present genus by Clusius). Rosaceje, 

 subfam. Spirkeae. SPIREA. Ornamental woody plants 

 grown for then- profuse handsome white, pink, or car- 

 mine flowers. 



Deciduous shrubs: Ivs. simple, short-petioled, den- 

 tate or serrate, sometimes lobed, rarely entire, without 

 stipules: fls. in umbel-like racemes, corymbs or panicles, 

 perfect, rarely polygamous; calyx cup-shaped or cam- 

 panulate, 5-lobed; petals 5, rounded; stamens 15-60, 

 inserted between calyx and disk; pistils usually 5, dis- 

 tinct, developing into follicles dehiscent along the inner 

 suture, with several minute oblong seeds. About 70 

 species in the temperate regions of the northern hemi- 

 sphere, in Amer. south to Mex., in Asia south to the 

 Himalayas. Many species formerly included under 

 Spiraea are now referred to other genera; see Physo- 

 carpus, Holodiscus, Sorbaria, also Cham&batiaria, Luet- 

 kea, Petrophytum, and Sibir&a for shrubby species, and 

 Aruncus. Filipendula, and also Astilbe for the herba- 

 ceous ones. There is a monograph of Spiraea and the 

 allied genera by Maximowicz in Acta Horti Petro- 

 politani, vol. 6, pp. 105-261 (1879) and a monograph 

 of the cult, species, with their numerous hybrids fully 

 described by H. Zabel, Die strauchigen Spiraen der 

 deutschen Garten (1893). There is much horticultural 

 literature on spireas, for the plants are popular and 

 about two-thirds of the known species and numerous 

 hybrids mostly originated in gardens are in cult. 



The spireas are very ornamental, usually low or 

 medium-sized shrubs with rather small deciduous 

 foliage and with small white or pink or sometimes 

 nearly crimson flowers in showy corymbs or panicles 

 followed by small inconspicuous capsule-like fruits. 

 Many are hardy North; some of the best of them are 

 5. arguta, S. Thunbergii, S. Vanhoutiei, S. pubescens, S. 

 trilobata, S. nipponica, S. media, S. ulmifolia, S. alba, 

 S. Douglasii, S. Menziesii, S. tomentosa. The recently 

 introduced S. Henryi, S. Veitchii, S. WUsonii, S. 

 Rosthornii and S. Sargentiana have proved hardy at the 

 Arnold Arboretum, while 5. blanda, S. japonica, and S. 

 albi flora require a sheltered position or protection dur- 

 ing the winter, though S. japonica and its allies, even if 

 killed almost to the ground, will produce flowers on 

 shoots of the same season. S. cantoniensis, S. Blumei, S. 

 chinensis, S. ctuiescens, and S. bella are more tender and 

 not to be recommended for the North, but are hardy or 

 nearly hardy in the middle states. S. prunifolia is 

 hardy as far north as Boston. 



In regard to the flowering season, the spireas can be 

 divided into two groups. The first one contains the 

 species of the section Chamaedryon, with white flowers 

 in umbels and blooming in spring, from April to June. 

 The second group is composed of the sections Calospira 

 and Spiraria, with white or pink flowers in corymbs or 

 panicles appearing from June to autumn. Some of the 

 most important species, arranged according to their 

 relative flowering-time, are the following: Early-flower- 

 ing spireas S. Thunbergii, S. arguta, S. hypericifolia, 

 S. prunifolia. S. media, S. pikoinensis, S. pubescens, S. 

 chamxdryfolia, S. trilobata, S. Vanhouttei, S. canton- 

 iensis, S. nipponica. Late-flowering spireas S. beUa, 

 S. Rosthornii, S. WUsonii, S. Henryi, S. Sargentiana, 



iv species 



group do not produce their flowers all at once like those 

 of the first group, but continue blooming for a longer 

 time. 



The spireas are all medium-sized or low shrubs and 

 well adapted for borders of shrubberies, as single speci- 

 mens on the lawn, or for rockeries. Especially the spe- 

 cies of the early-flowering group possess a graceful 

 habit and make effective single specimens, except per- 

 haps S. chamxdryfolia and S. media, which are some- 



what stiffer and less handsome and produce suckers. S. 

 canescens, S. Henryi, and its allies have the graceful 

 habit of the first group. S. japonica and its numerous 

 hybrids form mostly low, round bushes and are pretty 

 as single specimens or in the border. 5. alba, S. Doug- 

 lasii, S. Memicsii, and their hybrids should be planted 

 in shrubberies only and especially in situations where 

 their spreading by suckers does no harm; they are 

 sometimes used for low ornamental hedges. For rock- 

 eries S. decumbens, S. betulifolia, S. corymbosa, S. densi- 

 flora, S. buUata, and some dwarf hybrids of S. japonica 

 are to be recommended. 



The species of the section Chainaedryon, and also S. 

 canescens and S. betta, should be pruned as little as pos- 

 sible only thinned out and the weak wood rempvea 

 while those of the sections Spiraria and Calospira can 

 be pruned more severely if necessary, since they pro- 

 duce their flowers at the ends of the young shoots. Some 



of the early-flowering spireas, especially S. arguta, S. 

 prunifolia, S. Vanhouttei, and S. Bumalda, are sometimes 

 forced. 



The spireas grow in almost any moderately moist 

 soil and do not stand drought well, the spiraria species 

 being generally more moisture-loving; S. tomentosa 

 thrives well only in a peaty or sandy soil, while those 

 recommended above for rockeries require a well- 

 drained soil and sunny situation. Propagation is by 

 seeds sown in spring and covered only slightly with soil, 

 or by hardwood or greenwood cuttings. The species of 

 Chamadryon grow very well from greenwood cuttings 

 under glass, while the spirarias are usually raised from 

 hardwood cuttings. The calospiras seem to grow 

 equally well in both ways. The spirarias are also often 

 propagated by division and by suckers. 



acuminata, 31. 

 acuta, 1. 

 acutifolia, 1. 

 adiantifolia, 12. 

 alba, 35, 43, 50, 55. 

 albiflora, 35, 55. 

 alpina, 7. 



agnilfffi folia, 12 13. 

 arbuscula, 38. 

 argentea, 21. 

 arguta, 3. 

 atrosanguinea, 31. 

 bella, 28, 29. 

 beihlehemensis, 51, 52. 

 betulifolia, 38, 41. 

 Billiardii, 53. 

 tlanda, 15. 

 Blumei, 11, 12. 

 brachybotrys, 43. 

 bracieata, 10. 

 bullata, 30. 

 Bumalda, 34. 

 California*, 53. 

 callosa, 31, 34. 



INDEX. 



cana, 6. 

 canadensis, 51. 

 canescens, 21. 

 cantoniensis, 14. 

 cornea, 49. 

 carpinifolia, 51. 

 chamsedryf olia, 19, 20. 

 chinensis, 16. 

 coccinea, 28. 

 confusa, 18. 

 conspicua, 44. 

 Constantly, 53. 

 corymbosa, 14, 37, 40. 

 cratsegifolia, 12, 37. 

 crenata, 1, 8. 

 creni/oito, 8. 

 crispifolia, 30. 

 cuntata, 21. 

 cuneifolia, 21. 

 decumbens, 42. 

 densiflora, 38. 

 Douglasii, 48, 52, 54. 

 tximia, 53. 

 expansa, 28, 29. 



fastigiata, 29. 

 flabellata, 1. 

 flagfttata, 21. 

 flagelliformis, 21. 

 flexuosa. 20. 

 fore-plena, 5, 14. 

 fonienaysiensis, 43. 

 Fontenaysii, 43. 

 Fortunei, 31, 44. 

 Forii, 33. 

 Froebeli, 34. 

 glabrata, 31. 

 glabreseens, 18. 

 grandiflora, 49 



suppl. 

 Henryi, 25. 

 hypericifolia, 1. 

 intermedia, 47. 

 japonica, 31, 35, 44, 



and suppl. 

 kumaonensis, 29. 

 lanceata, 14. 

 lanceolate, 14, 50. 

 latifolia, 51. 



and 



