8 PLANTS 



HI. Phyllotaxy 



12. Recall the opposite and whorled types of phyllotaxy. 



13. a. Arrangement of leaves in grasses (Zea Mays). 



b. Arrangement of leaves in sedges (Carex). 



c. Arrangement of leaves in sour wood (Oxydendron), oak (Quer- 

 cus), etc. 



d. Arrangement of leaves in mullein (Verbascum), goldenrod 

 (Solidago), Easter lily (Lilium Harrisii). 



e. Arrangement of leaves (scales) in pine (Pinus). 



IV. Morphology of the Leaf 



14. Structure of a typical simple leaf (Pyrus). Identify: blade, petiole, 

 stipules and (in the blade) midrib, veins, and veinlets. 



15. Types of venation: Reticulate a. Pinnate (Castanea), b. Palmate 

 (Ampelopsis Veitchii). Parallel c. Basal (Convallaria), d. Costal 

 (Canna). 



16. Form of the margin of simple leaves. Find examples among the 

 leaves already studied of a. Entire, b. Serrate, c. Lobed. In 

 addition draw one that is d. Parted (Ricinus), and e. Divided 

 (Bidens). 



17. Compound leaves: a. Pinnately compound (Robinia) note rachis 

 and leaflets, b. Palmately compound (Parthenocissus). 



1 8. Structure of the blade, a. With the edge of the scalpel strip off the 

 thin membrane (epidermis) covering the upper and lower surfaces 

 of the blade (Caladium). Study the epidermis with a hand lens and 

 with a needle determine the texture, b. With the lens study both 

 surfaces of the green part of the blade (mesophyll) where the epi- 

 dermis has been removed. The denser portion is palisade mesophyll, 

 the other, spongy mesophyll. Determine texture with the needle. 



c. Scrape out some of the mesophyll and soak it for a time in alcohol 

 in a test-tube. Note the result. The green matter is chlorophyll. 



d. Can you find pores (stomata) in the epidermis? 



V. Stems and Roots 



19. Study a cross section of a stem (Paulo wnia) (Sambucus). Determine 

 the texture of the wood, pith and bark. 



20. Study a similar stem in longitudinal section in the region of the 

 node, as in 19. 



21. Compare the root of a similar plant with the stem, as in 19 and 20. 



