INTRODUCTION TO PLANT HISTOLOGY 



469 



Fusiform initial 



Medullary ray 

 initial 



Fig. 456. — Ulmus procera. Tangential view of the 

 cambium in a woody stem, showing elongated 

 cambial elements and einbryonic medullary rays. 



Fig. 457. — Types of trichomes. A, Lavandula i^ era. Branched hair. B, Galium aparine. 

 Climbing hair. C,Phaseohis multiflorus. Hooked hair. D, Primula sp. Multicellular 

 glandular hair. E, Calophyllutn sp. Multicellular hair. F, Begonia imperialis. Multi- 

 cellular hair with internal sclereid. G, Humulus lupulus. Grapnel hair. 



