52 THE TRANSVERSE SECTIONS OP PETIOLES OF EUCALYPTS 



The first and most general division is based upon the presence or absence of 

 central canals. 



Then such a limited Section as I. is comparatively easily disposed of. The 

 cortical cavities are either large or small. 



Section I. 



A. Cortical Cavities large — 



1. Hard Bast well developed — 



1. E. maculata. 



2. Hard Bast poorly developed — ■ 



a. Leaves, lemon-scented, and equally green on both sides — 



2. E. maculata, var. citriodora. 



b. Leaves unequally green on both sides — 



3. E. calophylla. 



B. Cortical Cavities small — 



4. E. ficifolia. 



In Section II. the first division may be based upon the leaves being equally 

 or unequally green on both sides. 



Section II. 



A. Leaves equally green on both sides — 

 1. Cortical Cavities large — 



a. Hard Bast w^ell-developed — 



A. Vessels of Wood relatively large — 



(1) Section small — 



5. E. cornuta. 



(2) Section large — 



(a) Epidermis very thick — 



6. E. tetraptera. 



{b) Epidermis thickish and wood-curve slender — 



7. E. obHqua. 



(c) Epidermis thinner and wood-curve thicker — 



8. E. gunnii. 



(3) Section of average size — 



{a) Section twice as broad as thick — 



9. E. megacarpa 



(b) Wood-curve always entire, and exceedingly 



thickened — 



XO. E. macrorrhyncha, 



