BOOK REVIEWS. 



24I 



found in woods. In this connexion attention may be called to Mr. 

 Dykes' curious test of habitat : any Iris whose leaves, on being held 

 up to the light, show small black spots, is a water-lover. On diseases 

 and their treatment there is a short and lucid statement : most 

 noteworthy under this head is the treatment recommended for the 

 " rot " which was so prevalent in English gardens a few years ago, 

 more especially as the obvious remedy of liming the soil is probably the 

 worst thing that can be done. It will perhaps be news to some that 

 most irises arrive from seed so quickly at flowering size : eighteen 

 months from the time of germination is given as a long enough period 

 for many bearded and beardless kinds, while a remarkable instance is 

 given of an /. pumila whose seeds germinated in spring and produced 

 plants which flowered the same autumn. 



Naturally such notes occupy but a small proportion of the text, 

 but, while the description of each species and subspecies includes an 

 exhaustive account of its distribution and introduction, with full 

 diagnosis (in Latin) and botanical description, matters which the un- 

 botanical gardener will perhaps pass over lightly, in most cases some 

 " observations " are added which are full of various interesting 

 details for the unlearned, with not a few acute inferences and con- 

 jectures. As an instance may be mentioned the suggestion that 

 /. albicans owes its introduction to Europe to the Mohammedan 

 invasion, since this plant was apparently planted regularly in the 

 cemeteries of the faithful : in that case it is probably of Arabian 

 origin and most likely an albino form of the blue Arabian iris known 

 as /. Madonna. 



Doubtless the most important scientific feature of the book is to 

 be found in the enormous advance which it makes towards a satisfactory 

 classification of the genus. Mr. Dykes has with infinite patience 

 worked through the bewildering mass of synonyms ; he has studied 

 each plant in its relation to its geographical distribution ; he has, in 

 a very large majority of cases, grown it himself, and seeded it j and 

 has made careful studies under the microscope, extending to the 

 pollen grains. 



The result is in general a great simplification of the current nomen- 

 clature, most of which of course rests on no authority. At the same 

 time the author is sometimes wisely content to draw provisional 

 lines : he has the caution of the really scientific mind. Here are 

 some of his results, which should be of interest to others besides 

 professed botanists : 



/. orientalis is distinguished from /. sibirica : many of the best 

 forms seen in gardens are crosses between the two, in which the 

 distinctive characters are blended. The spuria group is greatly 

 simplified, and we may part, without much regret, with such a name 

 as Guldenstadtiana ; it is even suggested that the three superb yellow 

 beardless flags known as ochroleuca, Monnieri, and aurea are sub- 

 species of spuria : incidentally we learn that the Cretan origin of 

 Monnieri is a myth. /. laevigata is distinguished from /. Kdmpferi 



VOL. XXXIX. R 



