90 Siidiloi Appearance and Constancy. 



In the case of the vast majority of sterile varieties 

 we know neither how, when nor wliere they arose. They 

 are propagated hy vegetative niethiods and have heen 

 from time immemorial. Bnt they differ from their sui)- 

 posed parent species so markedly that they take rank 

 with the hest varieties. Nobody suppc^ses that they have 

 arisen gradnally. 



The first instance that I give is Liliuni candiduni 

 plcnnni, a form which is on the market. It is a well- 

 known variety, the bnlbs of wdiich are offered every year 

 by dealers in bulbs, in their catalogues. Instead of 

 flowers it has long stalks clothed with petals (Fig. 13). 

 The stalk is the elongated thalamus ; the petals are nar- 

 row and dead white, and of the color and structure of the 

 petals of other white lilies. In each flower they continue 

 to appear for several weeks ; the lowest may be brown and 

 withered before the tippermost have unfolded. Figure 

 13 shows a fairly short flower; they are often twice as 

 long. Stamens and carpels are never formed ; the apex 

 consists of a compact bud of the youngest petals. 



We do not know how the variety first arose. It was 

 first described by G. Vrolik in 1827, after he had al- 

 ready seen it flowering for 20 years in the Botanical 

 Garden in Amsterdam.^ It is therefore nearly a century 

 old. In horticultural literature it is not referred to until 

 much later, about 1840.- 



Another well-known sterile garden plant is the green 

 Dahlia (Dahlia Tariahilis viridiflora). The flowerheads 



' G. Vrolik, Over cen rankvormig,c oniivikh cling van zvittc Iclic- 

 blooncn. Vcrhandclin^cn dcr cerste klassc v. h. k. Nederl. Institmit 

 van Wet. te Amsterdam, Part I, 1827, pp. 295-301, with one table. 

 The spike with five flowers figured there, is still preserved in our 

 collection. 



"See Mkrat, Ann. Soc. d'hortic. de Paris, 1841-1845, and Verlot^ 

 loc. cit., 1865, p. 91. 



