no 
L. Cockayne 
other of the varieties (not of necessity the parental one), while self- 
pollinated and inter-varietal hybrids will add more diversity. In 
this way a medley of forms may arise, whose history cannot possibly 
be guessed, and which might defy genetic research. 
The total number of possible hybrids given in the list at the end 
of this paper is 128. This number is certainly too small, even if 
considerable allowance be made for the inclusion of doubtful cases. 
The families affected number 33 (30 per cent, of the spermophyte 
families of the flora) and the genera 55 (16 per cent.) of which four 
are endemic. The only families and genera containing any consider¬ 
able number of hybrids are: Composited. 42, Scrophulariaceee (Ver¬ 
onica) 16, Celmisia 12, and Olearia 11; the three last-named may be 
considered palaeozelandic. For these families and genera the totals 
are certainly too low, while there are other genera which probably 
contain more hybrids than given in the list, especially Uncinia, 
Clematis, Ranunculus, Pittosporum, Rubus, Accena, Hoheria, Pimelea, 
Epilobium, Gaultheria, Dracophyllum, Gentiana, Coprosma and 
Cotula. Further, the following genera, not in the list, most likely 
contain a certain number of hybrids: Potamogeton, Agrostis 1 , Carex, 
Juncus, Luzula, Thelymitra, Colobanthus, Cardamine, Carmichcelia, 
Metrosideros, Oremyrrhis, Halorrhagis, Calystegia, Ourisia, Euphra¬ 
sia, Plantago, Wahlenbergia 2 and Craspedia. 
The only flora, rather larger than that of New Zealand 
but occupying about the same area, of which I have statistics 
is that of the British Isles. This, according to The London Catalogue 
of British Plants (10th ed. London, 1908) contains 251 hybrids, or 
nearly twice as many as in my list, but this total includes no less 
than 59 hybrids of Salix, 33 of Epilobium, 21 of Carex, 18 of Rubus, 
13 of Rumex and 12 each of Euphrasia and Potamogeton, while the 
genera concerned are three less than in New Zealand 3 . 
Coming next to the growth-forms of the New Zealand hybrids 
the following is the number for each in the comprehensive classes: 
trees 17, shrubs 49, semi-woody plants 28, perennial herbs (in a re¬ 
stricted sense) 18, grass-like plants 6, tussocks (including Phormium 
and Astelia) 4, woody Hanes 4, shallow-water plants 2. 
1 I follow Hitchcock in referring Deyeuxia Forsteri to Agrostis (The Grasses 
of Hawaii, pp. 149-50, Honolulu, 1922) and I look upon some of the varieties 
in the Manual, pp. 868-69, as species. 
2 N. E. Brown has shown that W. gracilis A. D. C. as defined in the Manual, 
p. 402, is a mixture of three species ( Gard . Chron. 54 , pp. 316, 317, 355). 
3 There is an interesting paper on Natural Hybrids by R. I. Lynch in the 
Report of the Conference on Genetics ( Journ . R. Hort. Soc. 31 , pp. 159-67, 
1906). 
