MATERIAL FOR STUDY OF PLANT HISTOLOGY 221 



Hairs and scales. Glandular hairs, " geraniums,'' most LabiaUr, sundew, 

 tomato ; ordinary unbranched hairs, leaves and stems of most Borraffinareai, 

 Gnaphallum, seeds of cotton ; scale-like hairs, leaves of Elaiagnus, olive, 

 Shepherdia; star-shaped hairs, leaves of Matthiola; stinging hairs, stem of 

 nettle ; T-shaped hairs, leaves and stems of Artemisias; branched hairs of 

 mullein. 



Laticiferous tissue. Root of chicory, of dandelion ; stem of Eujihorhia 

 splendens, of lettuce ; bract of Ficus elastica. 



Leaf structure. Hydrophytic : Elodea, Potaniogcton, submerged leaves 

 of Sagittaria; mesophytic : most deciduous trees and shrubs; xero[)liytic : 

 see under Cuticle, — also bearberry, crowberry, Eluiagnus, holly, oleander, 

 mistletoe, olive. 



Lenticels. Young twigs of birch, cherry, elder, and sumac. 



Leucoplasts. Pseudo-bulbs of Phajus grandlfolius, rootstocks of Iris gcr- 

 manica. 



Nuclear division (mitosis). Pollen mother cells of lily and its allies ; cells 

 of root tip of onion or hyacinth. 



Nuclei. Epidermal cells of many leaves ; growing points of roots or 

 stems ; hairs of roots, stamen hairs of Tradescantia, hairs of stem of cucum- 

 ber ; internodes of Tradescantia ; bulb scale of onion; pollen mother cell.s 

 of lily and its allies. 



Oil and resin glands. Aments of the hop ; hairs and emergences on leaves 

 of any aromatic Labiatm ; leaves of Eucalyptus globulus, of L'uta ; rind of 

 lemon or orange. 



Oil as reserve material. Oily seeds, as almonds, Brazil nuts, cacao seeds, 

 castor beans, peanuts, squash seeds, sunflower seeds. 



Pcdisade cells. Leaves of beech, Cycas, English ivy, Ficus elastica, holly, 

 Japan quince, mistletoe, oleander, poplar, privet, willow, yucca. 



Pollen tubes. Pollen of snowdrop (Leucojum), sweet pea, Tropaoluui, 

 tulip. 



Root, dicotyledonous. Beans and other Leguminosa', Composita\ gi-apevino. 

 primrose, Ranuncidus ; very young roots of most hardwood shrubs and 

 trees. 



Boot, monocotyledonous. See Central cylinder of root. Also asparagus. 

 Aspidistra, corn and other large grasses. Iris, sedges, Stnilax. 



Rootcap. Monocotyledonous: corn and other grasses, Iris: dicotyledo- 

 nous : bean, pea, sunflower, Tradescantia grown in water. 



Root hairs. Most roots of very young seedlings from seeds sprouted on 

 wet paper in a slightly damp atmosphere, Tradrsrantia grown in water. 



Sclerenchy ma fibers. See Bast fibers and Woodfbcrs. 

 • Secondary thickening. Twigs two years old and more of coniferous and 

 of hardwood trees. 



