34 ULMACEAE 



minute ducts sometimes in evident tangential lines, and fine 

 medullary rays; slender terete zig-zag twigs; small rounded 

 continuous pith; alternate 2-ranked half-round somewhat 

 raised leaf-scars; sessile round-ovoid buds with several 2- 

 ranked scales, the end-bud absent; short-petioled sometimes 

 oblique rather small and thick toothed leaves; small perfect 

 apetalous clustered flowers appearing before the foliage; and 

 small rounded blunt-spiny fruit. 

 Leaves ovate, unequally biserrate. P. aquatica. 



ZELKOVA. 



Deciduous rather small trees with slender twigs; small 

 pith; alternate 2-ranked scarcely raised half-elliptical leaf- 

 scars with 3 bundle-traces; minute transverse stipule scars; 

 ovoid sessile often collaterally multiple buds with half-a-dozen 

 exposed scales in several ranks; short-petioled oblique toothed 

 rather small leaves; inconspicuous often imperfect apetalous 

 flowers; and small drupe-like fruits. 



1. Leaves large (4X8 cm.), acuminate. Z. serrata. 

 Leaves smaller (scarcely 3X6 cm.), not acuminate. 2. 



2. Leaves lanceolate, rather long (4-5 cm.). Z. Davidii. 

 Leaves elliptical or ovate, short (3-4 cm.). Z. ulmoides. 



CELTIS. Hackberry. 



Rather ovoid much branched deciduous trees, or occasion- 

 ally shrubs, with variously roughened or warty bark; hard 

 pale or red-brown wood with a vernal zone of medium-sized 

 ducts and smaller summer ducts in a wavy transverse pattern, 

 and fine medullary rays; slender sometimes grooved sympodial 

 zig-zag twigs with somewhat angular pale pith chambered in 

 places; alternate 2-ranked appressed small buds with several 

 2-ranked scalesi; crescent-shaped leaf-scars with 3 bundle- 

 traces; minute stipule-scars; ovate-lanceolate truncately or 

 cordately oblique moderate-sized often serrate simple leaves; 

 small monoecious greenish apetalous flowers solitary or few 

 together; and small sugary drupes with reticulate or pitted 

 stone. 



