592 



FUCACEAE. 



2. Turbinaria tricostata Barton, Trans. Linn. Soe. Bot. II. 3: 218. vl. 54 f 3. 

 1891. 



On surge-swept rocks, low-littoral. New Providence. South Cat Cay, and Gun 

 Cay: — Bermuda to Guadeloupe. Type from Guadeloupe ( ?). 

 Apparently intergrading with T. turbinata. 



3. SARGASSUM Ag. Sp. Alg. 1: 1. 1820. 

 Floating and sterile. 



Leaves very narrowly linear or linear-filiform, mostlv 1-2 mm. 

 aculeate-acuminate ; vesicles commonly aristate-apicu- 



broad, the teeth 

 (S. nutans. 



late. 

 Leaves linear or linear-lanceolate, mostly 2-4 mm. broad, 



the teeth triangular-acuminate ; vesicles muticous. 2, S. f.uitans. 



Tsormally attached (nos. 3 and 10 sometimes more or less 

 pelagic). 

 Leaves mostly narrowly linear, usually 7-50 times as 

 long as maximum width. 

 Leaves rather rigid, cryptostomata usually somewhat 

 obscure, pedicels of the muticous vesicles com- 

 monly shorter than the vesicles themselves ; 

 receptacles in rather short axillary clusters. 

 Leaves serrate-dentate, the costa prominent and 

 often dentate ; vesicles commonly large and 



crowded ; stems often 1-2 m. long and subsimple. 3. 8. pteropleuron. 



Leaves subentire, the costa not dentate ; vesicles 



usually scattered ; stems mostly 2-10 dm. long. 4. 8. cymosum. 



Leaves thinly membranous, cryptostomata obvious, ped- 

 icels of the often appendaged usually scattered 

 vesicles commonly of about the same length as 

 the vesicles themselves ; receptacles finally elon- 

 gate and often forming a kind of loose terminal 



panicle through reduction of the leaves. 5. 8. Filipendula. 



Leaves ovate, ovate-elliptic, oblong, lanceolate, or rather 



broadly linear. 



Cryptostomata elevated, very large and conspicuous 



(0.6-0.9 mm. in maximum diam.) often elliptic, 



in a single series on either side of the costa ; 



leaves linear or lanceolate. 6. S. platycarpum. 



Cryptostomata smaller, sometimes obscure or wanting. 

 Cryptostomata obvious. 



Receptacles mostly in a rather dense terminal 

 panicle : leaves lanceolate or linear-oblong, 

 rather obscurely and obtusely dentate or 

 margins merely sinuate, cryptostomata in 

 almost a single series on either side of the 



costa ; vesicles sometimes few. 7. 8. lendigerum. 



Receptacles obviously lateral and axillary, 

 elongate or contracted ; cryptostomata in 

 more than a single series. 

 Leaves linear or linear-oblong, mostly 4-8 

 times as long as broad, sharply sei'rate- 

 dentate ; vesicles mostly ellipsoid or ob- 

 ovoid, often subapiculate : receptacles 



contracted, often (9?) spinose-dentate. 8. 8. vulgare? 



Leaves ovate, elliptic, oblong, or lanceolate, 

 mostly 2-4 times as long as broad, com- 

 monly crisped, variously aculeate-dentate 

 or 7/ej?-toothed ; vesicles globose or sub- 

 globose, muticous ; receptacles sometimes 

 elongate, occasionally with a few sub- 



spinescent processes. 9. 8 pohjceratium. 



Cryptostomata obscure or wanting : leaves cori- 

 aceous, oblong-elliptic, spinescent-dentate or 

 entire or sub-entire ; receptacles more or less 



spinescent-dentate. 10. 8. Hystrix. 



1. Sargassum natans (L.) Meyen, Wiegm. Arch. Naturgesch. 4r: 185. 1838. 

 Fucus natans L. Sp. PI. 1160. 1753. 

 Fucus Sargasso S. G. Gmel. Hist. Fue. 92. 1768. 

 Fucus hacciferus Turn, Hist. Fuc. 1: 105. pi. 47. 1808. 

 Sargassiun hacdferum Ag. Sp. Alg. 1: 6. 1820. 



The chief ingredient of the " Sargasso Sea " — found floating or washed ashore 

 throughout the archipelago. 



