572 SUMMARY OF CURRENT RESEARCHES RELATING TO 



fork in a normal condition, showing the characters of the bud-scales and 

 the extent of the decurrence of the segments on the secondary and 

 primary internodes. Rejecting the massing of the American species due 

 to Hooker and Baker, the author adopts the four sections founded by 

 Diels — DipJopterygium, Holopterygium, Acropterygium, Heteropterygium. 

 He supplies a clavis to the eighteen North American species, and pro- 

 ceeds to treat the species individually, describing four of them as new. 



Genus Cyathea in the West Indies.* — L, M. Underwood treats 

 of the distribution of the genus Cyathea in the "West Indies. The 

 common West Indian species, G. arborea (1793) is thetyiae of the genus. 

 There are about 200 species nearly equally divided between the tropics 

 of the Old World and the New. About 104 species are nearly equally 

 divided between North and South America. No species are common to 

 the Old World and the New. With two or three exceptions, no species 

 are common to North and South America. Each species is as a rule 

 local in its distribution. C. arhorea alone is common to the Lesser and 

 all the Greater Antilles. C. in sign is is common to Cuba and Jamaica ; 

 C. pubescens to Jamaica and Porto Rico ; C. Tussacii to Jamaica and 

 Hispaniola ; G. muricata to Guadeloupe and Martinique ; C. tenera to 

 Trinidad and the Lesser Antilles. Endemic in single islands are — 

 Cuba 3, Porto Rico 1, Jamaica 9, Dominica 1, St. Vincent 1, Trinidad 2. 

 In Jamaica the endemic species occur only at altitudes above 3000 ft., 

 or even 5000 ft. The higher altitudes of Cuba and Hispaniola need to 

 be explored. The following morphological and physiological features 

 require investigation : — («) Marked structural differences in shape and 

 arrangement of leaf-scars, supposed to be due to differences of nutrition 

 and consequent rapidity of growth, {b) The function of certain gland- 

 like structures at the bases of the leaves in certain species, and at the 

 bases of the pinnte in others, (c) The origin of pendent lateral bud- 

 like branches (especially in Gyathea dissoluta), organs of vegetative 

 reproduction. 



Validity of Polystichum Lonchitis and P. aculeatum.f — P. Lach- 

 mann and L. Yidal discuss the specific value of the distinctive characters 

 of Polystichum Lonchitis and P. aculeatum. After a careful comparison 

 of the two plants, they come to the conclusion that they are specifically 

 distinct : (1) in the amount of division of the frond, which in P. Lon- 

 chitis is pinnate, but in P. aculeatum is bipinnate or bipinnatisect ; (2) in 

 the number of vascular bundles passing into the leafstalk at its insertion 

 on the stem — two in P. Lonchitis, three or four in P. aculeatum ; (3) in 

 station and habitat, for P. Lonchitis occurs on rocks on high mountains ; 

 and P. aculeatum in woods in the plains or on the lower mountains ; 

 (J:) by their degree of polymorphism, insignificant in P. Lonchitis, but 

 extremely marked in P. aculeatum. They hold also that (5) P. 

 Pluhenetii is a young or dwarf form of P. aculeatum, and should be 

 struck out of systematic lists ; and that (6) to unite P. Lonchitis and 

 P. aculeatum on the strength of intermediate forms would necessitate 



* Torreya, vii. (1907) pp. 106-7. 



t Bull. Soc. Bot. France, liii. (1906) pp. 103-16 (figs.). 



