A ai A 
1878. } Glandular Hairs of Plants. 277 
Sachs says, “The first indication of the formation of hairs 
occurs in the papillose protuberances of the epidermis of many 
petals, to which their velvety appearance is due. To the simplest 
forms belong also the root-hairs which grow from the epidermis 
of true roots or underground stems (Pteris aguilina and eguisetum), 
they are thin-walled bag-like protuberances of the epidermis cells 
which lengthen by growth at the apex.” 
The Petunia of our gardens is rendered sticky and unpleasant 
to the touch on account of one-celled glands raised 
alate cated 
Fe ee! eer A ee ee re Oe Ee eS ee Pt OEE Sy Ce ee ee eee eee TN Pw oe eS Pn aa ee a) Ee 
AR TF MENETE 7 STFI 1 aana i yee e ELAT 
Fic. 23. 
Glands on Scrophularia 
nodosa. 
Fic. 26. 
A Top of gland. 
on a stem of two to seven cells. Scrophularia nodosa, the figwort 
of our rich bottom lands, has numerous glands on its surface. 
These are composed of one, two, three or more cells raised on a 
short stalk. Some of the larger glands are more expanded into 
flattened spheres, and are much like those found on our garden 
verbenas next to be mentioned. The gland of the garden ver- 
bena consists of a large cluster of about thirty-five cells at the tip 
of a delicate stalk. The top of the gland is seen in Fig. 26, and 
appears to have about thirty rays and some central pieces of 
irregular shape. The lower surface of the gland, when it breaks 
off, shows two rings, one within the other. The inner is seen 
first, and on turning down the tube of the microscope the outer 
_ ting isseen, The gland is full of a purple substance. Figs. 27 
_ and 28 exhibit the four-celled glands of the tomato plant. Each 
cell, as in many other cases, shows a nucleus, and some of them 
; 
i Fic, 21. 1G, 22. Fic. 24. 
Glandular hairs of Petunia. Glandular hair of Verbena. 
ae ee a a 
