Nov., 1906.] Pubescence of Ohio Plants. ii 



Phlox pilosa; for appressed pubescent leaves Hydrophyllum vir 

 ginicuni; for ciliate leaves Valeriana sylvatica. 



Only 37 of the 904 pubescent plants are stellate-pubescent, 

 but these are very striking. The butternut, Juglans cinerea, has 

 stellate pubescent leaves, and also four of the oaks ; Quercus nana, 

 Quercus marylandica, Quercus minor and Quercus prinoides. 

 The most pronounced of this type, however, are the two crotons, 

 Croton capitatus and Croton monanthogynus. 



Of the glandular pubescent forms there are 58. Many plants 

 have stems of this type without having the leaves to correspond. 

 About half of the roses, as well as Rhexia virginica and Scutel- 

 laria cordifolia have glandular hairs on the stems. One of the 

 most striking forms in the plant kingdom, the Drosera or sun- 

 dew, belongs to this group. 



There are 67 tomcntose forms but all of them are not constant 

 throughout their whole life. About one-half of those which are 

 tomentose when young become either glabrous, glabrate or 

 slighlty pubescent when mature. Many of the oaks, among 

 them Quercus platanoides. and Quercus minor, are densely to- 

 mentose on the under side of the leaves. The young twigs of 

 Quercus minor are also tomentose. Viburnum alnifolium is in- 

 teresting in being one of the few which is stellate-tomentose. 



532 plants were found to be entirely glabrous, that is, having 

 both sides of the leaves and the twigs entirely free from hairs 

 throughout their whole life; but 1019 were found to have one 

 or more glabrous parts. The spring beauty, Claytonia virginica, 

 and wake-robin, Trillium grandiflorum, are common examples 

 of the former; Cercis canadensis and Aster laevis of the latter. 



Of the glaucous forms there are 59. The glaucous bloom of 

 twigs and leaves is identical with that on some fruit, such as 

 plums and grapes, but that on leaves is not usually so noticeable. 

 It may be seen on the under side of the leaves of Salix glaucophyl- 

 la and Salix myrtilloides, and on the stems of Vitis bicolor and 

 Helianthus grosseserrattis. 



The granular and scurfy forms are comparatively few in num- 

 ber, only about 24 of the former, and 34 of the latter. The upper 

 surfaces of the leaves of Silene armeria and of Amaranthus bli- 

 toides are granular. All of the chenopods are scurf v. 



This leaves only those which are resin-dotted, punctate, or 

 have peltate scales. There are 106 in the division, and it is per- 

 haps the most interesting group of all. Beautiful peltate scales 

 are found on Hicoria minima and on Chamaedaphne calyculata. 

 Resin-dots are found on many, among them being Ribes 

 floridum, Gaylussacia resinosa and Glecoma hedercacea. The 

 most strikingly punctate are the polygonums and the hypericums. 



