79 

 NOTES ON SOME HONOLULU PALMS— 11 L 



Vaughan MacCaugiiev — The College of Hawaii. 



TJic Slender Ean-Palms — I hrinax. 



Thrinax is a Greek word for fan. The palms of this genus 

 are characterized by their fan-shaped leaves and slender trunks. 



There are nine or ten species of Thrinax, all confined naturally 

 to the tropics of the New World. They are distributed from> 

 Southern iTorida through the West Indies to the shores of Cen- 

 tral America. They are now used as pot-plants and ornamentals 

 in man}'- parts of the world. The species that is common in the 

 Honolulu region is the Thrinax argentea. Those grown in pots 

 or tubs are young or stunted plants, and have little or no stem; 

 those grown out of doors in the ground attain mature stature, 

 with tall, slender trunks (see fig. 1). 



The Thrinaxes are small palms, rarely over 15 to 20 feet in 

 height. In the cultivated species there is but a single stem to a 

 plant, the others either not developing or being pruned away. In 

 the case of several of the wild forms, however, the palm sends 

 up from the ground a number of stems, forming a clump or 

 group. The lower portion of the trunk is marked by the ring- 

 like scars left by the falling leaves ; the upper portion is more or 

 less clothed by the fringed leaf-sheaths. The rind, or outer layer 

 of the stem is pale gray, almost as light in color as the rind of the 

 royal palm. The wood is light and soft, with numerous small 

 fibro-vascular bundles. The exterior of the stem is much harder 

 than the spongy interior. According to Sargent, in the Southern 

 States "the stems are used for the piles of small wharves and 

 turtle crawls" (traps). 



The leaves of Thrinax form a loose, graceful crown at the 

 summit of the slender stem. The leaf-blade is orbicular. It is 

 thick and firm in texture and is conspicuously folded or plaited, 

 like a fan. The plaits or segments are separated near their ends, 

 and the ends themselves are forked or split. The rind is either 

 quite short or entirely lacking. At the center of the upper sur- 

 face of the blade, above the point where the petiole is attached, 

 is the conspicuous, elevated, concave ligule. While young it is 

 lined with a silvery wool. This conical, pointed ligule is one of 

 the characteristics of the Thrinaxes, distinguishing them from 

 other palms. 



The petioles are long, slender, and arched by the weight of the 

 blade. In cross section a petiole is biconvex, and its margins are 

 smooth. The leaves of palms are characterized by the peculiar 

 and interesting sheaths that encompass the bases of the petioles. 

 These sheaths are composed of stout, interlacing fibers, which 

 form a coarse fabric-like material, and indeed are utilized as 

 such by many semi-civilized peoples. The sheaths of the 



