CONFERENCE ON ASTERS AND PERENNIAL SUNFLOWERS. 3 



unisexual. Bellis differs mainly from Aster by the entire want 

 of a pappus. There is an Aster which is common in the Swiss 

 Alps which is exactly like a Daisy in habit. The heterogamous 

 AsteroideaB fall into two groups, a heterochromous series, in 

 which the ligulate ray-flowers are lilac, or reddish, or white, 

 and a homochromous series, in which the ray-flowers are yellow. 

 The best-known genus of the homochromous series is Solidago. 

 Aster as it stands at present contains 200 or 300 species, and is 

 concentrated in the United States. I will not attempt on the 

 present occasion to discuss its subgenera and species in detail. 

 I dealt with them fully in a paper which I contributed to the 

 Gardeners' Chronicle in 1884, and all that I could say further 

 now would be that a small number of additional species have 

 been brought into cultivation. Nearly all our garden Michaelmas 

 Daisies belong to the species that grow wild in the eastern 

 United States. There are forty species of Aster in the Eocky 

 Mountains and fifteen in California, and most of these are 

 different from the eastern species, and have not yet been brought 

 into cultivation. Erigeron only differs from Aster by its more 

 numerous narrower ray-flowers, and runs into it by gradual 

 stages of gradation. Olearia, of which there are sixty to seventy 

 species in Australia and twenty to thirty in New Zealand, differs 

 mainly from Aster by its shrubby habit. 



Helianthoidese is another large tribe, of which many of the 

 140 genera only differ from one another by very slight characters. 

 In a large proportion of them the heads are heterogamous and 

 homochromous, the ray being bright yellow. Helianthus in a 

 wild state is entirely confined to North America. Several of the 

 genera that are allied to it most closely, such as Wedelia, 

 Aspilea, and Viguiera, are not hardy. Coreopsis has a different 

 pappus, Eudbeckia may be distinguished at a glance by its very 

 prominent disc, Helianthella by its flattened fruits, Silphium 

 and Heliopsis by their large leafy outer involucral bracts. A 

 very interesting paper might be written on the way in which 

 the three commonest garden types, H, multiflorus, annuus, and 

 tuberosus, have been changed by cultivation through a long- 

 course of years from their wild originals. The species are 

 extremely difficult of limitation. I will only say that I think 

 they may be best classified under three groups — first, the 

 annuals ; secondly, the perennials, with short adpressed 



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