98 



Cirsiu?n), 7; Centaurea, 2; (none in Hieracium); Sonchus, i; 

 Tragopogon, i; Vaccinium, i; Erica, 4; Limonium, i; Armeria, i; 

 Primula, 3; Erythraea, i; Gentiana, i; Symphytum, i; Verhascum, 

 5; Scrophularia, i; Euphrasia, 16; Utricularia, i; Pingnicula, i; 

 Mentha, 8; Scutellaria, i; Prunella, i; Stachys, i; Lamium, i; 

 Ajuga, I; Chenopodium, i; Salicornia, 5; Polygonum, 8; Rumex, 

 16; Euphorbia, i; Ulmus, 3; Betula, i\ ^uercus, i; Salix, 70 

 (many multiple); Populus, i; Epipactis, i; Anacamptis, i 

 (bigeneric, with Gymnadenia); Orchis, 15; Ophrys, 4; Gymna- 

 denia, 6 (all bigeneric with Cocloglossum, Leucorchis, and Orchis); 

 Coeloglossum, 1 (both bigeneric with Orchis); Platanthera, i 

 (bigeneric with Orchis); Juncus, 3; Luzula, i; Sparganium, i; 

 Potamogeton, 19; Zostera, i; Scirpus, i; Carex, 31 ; Alopecurus, i; 

 Polypogon, I (bigeneric with Agrostis); Koeleria, i; Glyceria, 3; 

 Festuca, 1; Agropyron, 1. In all, 303 plant forms regarded as 

 hybrids, eleven of them between different genera. We are 

 usually left to assume that these are first generation hybrids, 

 but this may not always be the case, and cannot be in the 

 multiple ^'^//x hybrids. 



The known polymorphism of certain species is only partly 

 dealt with and it is stated that the many forms of Capsella and 

 Taraxacum have been purposely omitted. Nevertheless, 46 

 varieties or races are listed under i?0J"« canina. Rosa involuta 

 and i?. hibernica, long considered species, now stand as hybrids. 

 I am glad to see Anagallis foemina Mill, {coerulea Schreb.) 

 given as a distinct species, as I have long so regarded it. The 

 dimorphism of Digitalis, observed by Miss Saunders, is not 

 recognized. 



A matter of special interest to us in America is the number of 

 species in several genera, as compared with the number in our 

 flora. Thus Britain is extremely rich in Rubus and Hieracium, 

 but very poor in Aster, Oxytropis, Clematis, ^uercus, etc. The 

 recent investigations of C. C. Hurst on Rosa may throw a flood 

 of light on these phenomena. The groups in which there is 

 great diversity, with a large number of species, may be expected 

 to be found, when their chromosomes are examined, to be 

 polyploid. Such polyploid species, according to Hurst's ob- 

 servations on Rosa, may give rise to diploids, which if they 

 survive will remain relatively constant, with only small varia- 

 tions. They can only do otherwise through a slow process of 



