BRITISH EUPHRASIA. 



Br CEDRIC BIJCKXALL, Mus. Bac. Oxox. 



' Since the appearance of Wettstein's Monog^raph (1893) and of 

 TownsencVs account of the British species of Euphrasia (Journ. Bot. 

 1897), many able botanists have interested themselves in the o-enus, 

 and by collecting specimens from all parts of ttie British Isles have 

 greatly extended our knowledge of the distribution of these plants, 

 besides adding four species, one of them new, to the British Flora. 

 Many of the forms are well marked and as a rule are correctly named 

 by collectors, but with others a wide diversity of opinion as to names 

 and position has clearly shown that in estimating the value of dis- 

 tinctive characters and in perception of the limits of variation we 

 still have much to learn. 



During the past twenty years I have collected examples of nearly 

 all the species described by Townsend in his Monograph, and have 

 examined a large number of British specimens contained in herbaria ; 

 while visits to Switzerland, Tyrol, North Italy, and parts of France 

 have made me acquainted also with a number of Continental forms. 

 Led by this experience I have arrived at the conclusion that, if closer 

 attention were paid to the general habit and more obvious characters 

 of these plants, their study would be much facilitated, and their 

 position could be determined with greater certainty. A preliminary 

 attempt in this direction is made in the analytical keys and in the 

 short diagnoses which follow, and in these more prominence is given 

 to certain characters than is apparent in the minute and elaborate 

 descriptions of Wettstein and Townsend, without, I believe, intro- 

 ducing an^^thing that is at variance with the descriptions or figures of 

 those authors. 



The characters of which I propose to make use are :— 1. Tlie 

 relative density or laxity of the entire plant, depending on the length 

 of the internodes between the cauline leaves and the branches, and 

 between the bracts of the fruiting-spike. 2. The relative length of 

 the leaves and bracts in the same plant, and their actual length in 

 different species. , -3. The length of the fruiting-spike in relation 

 to the entire stem, and whether it is stout or slender. 4. The shapj 

 of the teeth of the fully developed upper bracts, viz. those of the 

 younger fruit or of the older flowers. This varies from triangular or 

 ovate to lanceolate and subulate and is often characteristic of the- 

 species. In some cases, however, the shape of the teeth is variable, 

 and too much reliance shoidd not be placed on it as a distinguishing 



JOUKXAL OF BOTANT, MaK., 1917. [SUPPLEMENT I.] b 



