260 208 



Closely allied to D. tetragona, D. megalodas and D. Poiteana; it resembles D. me- 

 galodus in venation and cutting but differs by its densely setose capsules and lack 

 of the adpressed stellate hairs on the leaf-tissue of the under-surfaces; from D. 

 Poiteana it differs by the dense stellate pubescence of stipe and rachis, the deeper 

 incised pinnæ and fewer anastomosing veins; as a rule only the basal pair of veins 

 are united into a free excurrent vein. From D. jiirnensis it differs by its not-granulose 

 surfaces and the not-bulbiferous rachis. 



262. Dryopteris tetragona (Sw.) Urban, Symb. Ant. 4: 20. 1903; C. Chr. Ind. 297. 



Syn. Polypodinin tetragomim Sw. Prod. 132. 1788: Schkuhr, Kr. Gew. I: tab. 18. 

 1 Polypodia m androgynum Poir. Enc. 5: 535. 1804. 

 Polypodium suhtetragoniim Link, Hort. Berol. 3: 105. 1833! 

 Polypodium imbricatum Liebni. Mex. Bregn. 58 (Vid. Selsk. Skr. V. 1: 

 210). 1849! 



(For other synonyms see Index Fil.). 



Type from Jamaica leg. Swartz (S!). As Swartz has named different forms 

 D. tetragonum I consider that form typical, which is figured by Schkuhr and which 

 agrees perfectly with the original diagnosis. 



D. tetragona has been considered a very variable species of a wide distribution, 

 and this is to a certain degree true, but I have found that about half the number 

 of the hundreds of specimens named tetragona and examined by me belong to more 

 or less allied species, which it is not difficult to distinguish from D. tetragona. The 

 common West-Indian typical form of this shows the following specific characters: 



Rhizome shortly creeping or obliquely erect with brown scales, which are 

 covered with stellate hairs. Stipes fasciculated like the rachis stramineous, quadran- 

 gular, slightly and very shortly hairy by stellate hairs. Leaves somewhat dimor- 

 phous, the pinnæ of the fertile leaves being narrower (2 cm br.) than those of the 

 sterile ones (2^'-» cm br.). Lamina ovate with 6 — 12 pairs (generally 8) of lateral pinnæ 

 and a similar terminal one. Pinnæ opposite or nearly so, short-stalked, oblong, 

 acuminate, the lower ones narrowed towards the base, about 10 cm long by 2 — 2'/3 

 cm broad, incised ' ■-■ or -/a of the way down into close, acute, entire segments, her- 

 baceous, dark-green, the under-surface generally nitid, glabrous on both surfaces, 

 excepting the costæ (which are flat with two low furrows) and costulæ beneath, which 

 are slightly hairy by spreading, simple, acute hairs, ciliate at the margins. Veins 

 simple, 8 — 10-jugate, the basal pair united and sending a branch to the sinus, the two 

 next free and reaching the margin immediately above the sinus. Sori inframedial, 

 exindusiate; sporangia setose. 



The form here described is very common in the West-Indies and there fairly 

 constant; nearly identical forms are found on the continent from Mexico to Ecuador; 

 the specimens herefrom have, however, generally a more dull under-surface. In the 

 following I enumerate the islands and countries, from which I have seen specimens 

 and add some of the more important collector-numbers. 



