PLANT TISSUES 



IOQ 



multicellular, non-glandular (simple) or glandular. The non- 

 glandular hairs may be of various shapes, viz. : clavate (club-shaped) 

 as on Rhus glabra fruits', stellate for star-shaped) as on Deutzia 

 leaves; candelabra-shaped, as on Mullein leaves; filiform as on 

 Hyoscyamus, Belladonna and Digitalis leaves; hooked, as on stems 

 of Phaseolus multiflorus or Hops; barbed, as on the stems of Loasa 

 species; or tufted, as found on the leaves of Marrubium vulgar e. 

 They may be simple as in Cotton, etc., or branched as in Hyoscyamus 

 muticus. 



The glandular hairs comprise those whose terminal cell or cells are 

 modified into a more or less globular gland for gummy, resinous or 

 oily deposits. They are generally composed of a stalk and a head 

 region although rarely the stalk may be absent. The stalk may be 

 unicellular, bicellular or uniseriate (consisting of a series of super- 

 imposed cells). The head varies from a one- to many-celled struc- 

 ture. The drug Lupulin consists of the glandular hairs separated 

 from the strobiles of Humulus lupulus. 



Scales are flat outgrowths of the epidermis composed of one or 

 several layers of cells. They occur attached to the stipes of Aspid- 

 ium, Osmunda and other ferns, where they are called "chaff scales." 

 They are also found on a number of higher plants. 



Plant hairs are adapted to many different purposes. They may 

 absorb nourishment in the form of moisture and mineral matter 

 in solution, e.g., root hairs. Those which serve as a protection to the 

 plant may be barbed and silicified, rendering them unfit for animal 

 food, or,-as in the nettle, charged with an irritating fluid, penetrating 

 the skin when touched, injecting the poison into the wound. A 

 dense covering of hairs also prevents the ravages of insects and the 

 clogging of the stomata by an accumulation of dust. They fill an 

 important office in the dispersion of seeds and fruits, as with their 

 aid such seeds as those of the milkweed and Apocynum are readily 

 scattered by the wind. 



The reproductive organs of many Cryptogams are modified 

 hairs, as the sporangia of Ferns. 



ENDODERMIS 



Endodermis is the "starch sheath" layer of cells, constituting 

 the innermost layer of the cortex. In Angiospermous stems it 



