534 MR. K. GROVES OX THE 



under the specific name of C. alba var. are perfectly bewildering; 

 and it would be well if the Tenorean species deusta were ad- 

 mitted, as it would have the advantage of separating two well- 

 marked sections, those of alba proper and the deusta varieties, 

 which are easily recognized by their physical aspect from the 

 former. la our district the deusta varieties hold undisputed 

 sway, growing usually at no great height above the sea, and 

 generally not removed far from it. They may be divided into 

 two sections, the large- and the small-flowered ones. The former 

 are tall handsome plants with robust angular stems and large 

 capitula presenting an oval shape before flowering, while the 

 latter have a much less stature, with subcorneal flower-heads 

 which are not a fourth part of the size of the former ; besides 

 which the plant is so much branched and diffuse as to appear 

 almost decumbent. Late in November of last year I met with a 

 Centaurea near Florence which might have been mistaken at a 

 short distance for a deusta variety of C. alba, until I observed 

 that the spots on the involucre-scales were apparently formed 

 by the application of a thick grass-green pigment, laid on, as it 

 were, in longitudinal lines, and that on the edges of the spots 

 there were a few detached lines of the same pigment having the 

 appearance of glands. Further examination led me to believe 

 that the plant must be a hybrid between C. alba and 0. amara, L., 

 the period of its flowering being that of the last-named species, 

 which is the most autumnal of all our Centaureas. Moreover, 

 the supposed hybrid shows some decided peculiarities when 

 withering which connect it with C. amara, whilst its root-leaves 

 partake of the alba type. Now in the south of Italy all the 

 deusta varieties that I have observed have either a black, brown, 

 or bluish macula, which has not the appearance of being laid 

 on, but of being merely a stain on the scale itself. Can the 

 deusta varieties have been brought about by hybridization as 

 well ? 



I w ill first describe the small variety of deusta found in our 

 district, inasmuch as it seems to be the furthest removed from 

 the typical alba form. 



Centaurea deusta, Ten., var. tenacissima, mihi. Aspera 

 fusca tenacissima, caule anguloso ad radicem ramosissimo corym- 

 boso ; foliis valde costatis in lacinias late lineares mucronatas 

 divisis, radicalibus bipinnatis saepe arcuatis, caulinibus piunatis, 

 auperioribus spathulatis, summis sub capitulo subconico parvo 



