THE CYTOLOGY OF BRITISH SPECIES OF EUPHRASIA 



105 



found. Roughly there are large, small, and intermediate sizes, the latter apparently in 

 the majority. Mostly there is one chiasma per bivalent, but one or more bivalents with 

 two chiasmata occur in most cells, both in tetraploids and diploids. In the tetraploids 

 no indications of multivalent formation were seen. 



The occurrence of an extra univalent in E. brevipila var. notata was not recognized 

 until a fair number of cells had been seen, and it is conceivable that iif could have been 

 encountered in previous work and overlooked. However, the fact that it was never 

 detected indicates that among the species in general it is rare, whereas its discovery in 

 two populations of var. notata indicates that it is relatively frequent in that form. Its 

 accompaniment by frequent pairing failure in one pair of chromosomes suggests that it 

 may be quite common in E. brevipila var. notata, at least around Lawers. 



Discussion 



Relation of Chromosome Numbers to Classification 



The two diploid species which von Witsch (1932) counted, E. montana and E. 

 rostkoviana, possess long glandular hairs, and fall in the Series Hirtellae, a group created 

 by Pugsley (1930), while all the other species previously counted were tetraploids with 

 n=22. This suggested that probably all the Hirtellae were diploids, and that all the 

 other members of the Subsection Ciliatae, together with the Subsection Angustifoliae, 

 were tetraploids. The counts obtained in the present work confirm this pattern, as far 

 as the Ciliatae are concerned. This is illustrated in the accompanying table. 



Table of British species o/ Euphrasia arranged according to Pugsley' s classification, with E. minima, showing their 



haploid chromosome numbers. 



SECTION SEMICALCARATAE 



Subsection Ciliatae 













Series Latifoliae 





Series Nemorosae 





Series Brevipilae 





micrantha 



22 



rotundifolia 





horealis 





scotica 



22 



marshallii 



22 



brevipila 



22 



rhumica 





curta var. rupestris 



22 



var. notata 



22 



frigida 



22* 



cambrica 





var. reayensis 



22 



foulaensis 



22 



occidentalis 



22 



Series Hirtellae 





eurycarpa 





nemorosa 



22 



rostkoviana 



11* 



campbelliae 





heslop-harrisonii 





montana 



11* 



(minima) 



22* 



confusa 



22 



rivularis 



11 







pseudokerneri 



22 



anglica 

 hirtella 



11 

 11 



Subsection Angustifoliae 



E. salisburgensis 22* 



* Chromosome number obtained from non-British material. 



These results confirm Pugsley's classification of the long-glandular species in a 

 separate group, the series Hirtellae. Previously they were placed partly in the Grandiflorae 

 Wettst. and partly in the Parviflorae Wettst., both of which groups also included eglandular 

 species. The cytological distinctness of the Hirtellae draws attention to the relative 

 isolation of the group. The species have one constant and almost diagnostic character, 

 namely the covering of long glandular hairs. In addition the capsule tends to be short 

 and broad, the calyx and seeds to be similarly proportioned, and the flower to have a 

 porrect lower lip, with the lobes not greatly emarginate or greatly dilated apically, and 

 a broad upper lip. They do not diverge to any great degree from the series Brevipilae, 



