61 113 



Subgenus 4. Lastrea Bory, emend. C. Chr. 

 Biologiske Arbejder tilegnede Eug. Warming p. 79. 1911. 



This subgenus is nearly identical with the group of Dryopteris opposita mono- 

 graphically dealt with in my former papers on American species of Dryopteris 

 (quoted above pag. 55). I have there in some details mentioned the charaters of 

 the group, and I have only a little to add to my earlier treatment. Still my 

 delimitation of the group must be somewhat changed, partly by including some 

 species, which have not a decrescent lamina, partly by excluding some few species, 

 which I now refer to the subgenus Glaphyropteris. 



The character: a lamina decrescens is, like all other single characters, not 

 available as standard-character, which all species of this subgenus have in common 

 and which is found only here. It is evident that a species as D. blanda (Fée) 



C. Chr. is a near relative of D. oligocarpa, although it has not the lamina nar- 

 rowed downwards. Our common Ü. tlielypteris is another instance of a species 

 having a non-attenuate leaf. Still such species are exceptions which affirm the 

 rule. Out of the 118 species enumerated below only 3 or 4 have not auriculiform 

 pinnæ. On the other hand species with a lamina decrescens are to be found also 

 within other subgenera, f. inst. Glaphyropteris and Steiropieris. In some species of 

 § Cyclosorus, f. inst. the typical D. mollis, the lamina is so much narrowed down- 

 wards as in most species of § Lastrea, and the same can be said on D. Safjordii 

 a species of § Eiidryopteris. 



The best and most constant character of ^^ Lastrea is the venation, as ex- 

 plained in my "Revision". The veins are always free, as a rule simple (in some 

 few species normally furcate), the basal ones nearly always reaching the margins 

 above sinus and not separated by a cartilagineous membrane as in species of 

 § Steiropteris and Cyclosorus. The frequent occurrence of sessile glands on the leaf- 

 tissue beneath and of aërophores at the base of the pinnæ are also characteristic 

 for the subgenus. In this paper I have excluded those species having aërophores at 

 the base of the segments and referred them to § Glaphyropteris, viz. D. Cahadazii, 



D. Thomsonii and D. macradenia. Most species are rather hairy by simple and, as a 

 rule, unicellular hairs; only in some very long-hairy species (D. mertensioides, D. Rui- 

 ziana, D. nitens, D. multiformis and some others) the long hairs consist of 2 — 4 

 cells, but such hairs are not very like the short, pluricellular hairs so characteri- 

 stic in species of § Ctenitis. The sori are in several species exindusiate, in others 

 furnished with a small, rarely persistent indusium. 



Since the publication of my earlier papers I have examined numerous speci- 

 mens of species belonging to § Lastrea, some of w'hich belong to species previ- 

 ously unknown to me and some others to species new to science. In the following 

 pages I give another supplement to my first paper, and the number of species is 

 now increased to 120. As seen from that number the subgenus is extraordinarily 



