OF THE AMENTUM. 189 



The name of Lvoolucrum is applied by Gleditsch 

 to the membrane covering the fructification of ferns, 

 f. 144, 145; nor have I, in studying this part with 

 peculiar attention in order to reform the genera of 

 these plants, see Tracts relating to Natural His- 

 tonj, p. 215, found reason to contrive any new 

 appellation. My learned friends Willdenow and 

 Swartz have judged otherwise, calling this mem- 

 brane the indusium, or covering; which seems to 

 'me altogether superfluous. See its various forms in 

 Engl. Bot. t. 145860, 1150, 1159, 1160, &c. 



3. Amentum,/. 146. Catkin, denominated by authors 

 before Linnaeus julus, nucamentum, or catulus; con- 

 sists of a common receptacle of a cylindrical form 

 beset with numerous scales, each of which is accom- 

 panied by one or more stamens- or pistils, so that 

 the whole forms an aggregate flower. The recep- 

 tacle itself and the bases of the scales are firmly 

 united, and the whole catkin falls off entire, except 

 that in some instances the upper part of each scale 

 withers away, as in the Willow genus, Saliv, Engl. 

 Bot. t. 138890, 1402 4, c., *the seed-vessels 

 in that genus being quite distinct from the scales. 

 In others, the whole scale remains, enlarges, hardens, 

 and protects the seed, as in Pimis, the Fir tribe. 

 Such is the case with catkins of fertile flowers, 

 which are necessarily permanent till the seed is ripe; 

 barren ones fall as soon as the stamens have per- 



