1903 Prakgkr. — The Flora of Clare Island. 293 



' As regards the floras of the two islands, they show a broad 

 similarity, and a remarkable parallelism is noticeable some- 

 times in the case of plants absent, as well as plants present. 

 For instance Rtimex conglomeratus and R. sangumeus are 

 absent, R. obtusifolius and R. crispus present in both floras — 

 all plants which one expect to find everywhere ; and a good 

 many similar cases occur. 



Coming to the total flora, the Clare Island list as given 

 above numbers 368 species and sub-species, or, omitting 

 CharacecB for the sake of comparison, 365. The flora of Inish- 

 bofin, according to the same standard^, numbers 303. A com- 

 parison shows that 251 of these are common to both islands ; 

 52 are found on Bofin and not on Clare, 117 on Clare and not 

 on Bofin. The *' index of floral diversity," according to Mr. 

 Colgan's definition^ would therefore be f|g or -44. This figure 

 may be compared with the corresponding indexes of several 

 pairs of Irish botanical divisions by reference to Mr. Colgan's 

 paper. It shows a higher degree of diversity than might have 

 been expected in the flora of two adjoining areas so similarly 

 situated. While a detailed comparison of the two floras would 

 take up too much space, a few of the leading dissimilarities 

 may be mentioned. The number of the representatives of a. 

 few orders is curiously out of proportion to the respective 

 total floras. Thus, Clare has seven Rosacea (ranking Ricbus 

 f}uticosus as one) not in Bofin, Bofin only two not in Clare. 

 Bofin, on the other hand, is distinctly richer in Ra7iunculacecB 

 and CrucifercB. Clere has no less than thirteen Composite not in 

 Bofin ; Bofin only two not in Clare. Clare is also dispro- 

 portionately rich in Amentifercs and OrchidacecB. The most 

 marked difference occurs among the Cyperaccce. Mr. More 

 considered that Bofin had its fair share of this order ; yet Clare 

 contains no less than thirteen species, including eights edges, 

 not in Bofin, and possesses every Bofin species also. Against 

 this, however, Bofin is unexpectedly rich in grasses, having 



^ Treating /unats conglomerattis and /. efficstis as separate species, and 

 omitting Festuca duriuscula as a variety. 



« Irish Nat., x., 236. The index of floral diversity is " the ratio which 

 the total of species not common to both areas bears to the total flora of 

 the two areas combined." 



