102 TREES OF NORTH AMERICA 



Class 2. ANGIOSPERM^. 



Carpels or pistils consisting of a closed cavity containing the ovules 

 and becoming the fruit. 



Division I. Monocotyledons. 



Stems with woody fibres distributed irregularly through them, but 

 without pith or annual layers of growth. Parts of the flower in 3's : 

 ovary superior ; embryo with a single cotyledon. Leaves parallel- 

 veined, alternate, long-persistent, without stipules. 



III. PALMiE. PALMS. 



Trees, growing by a single terminal bud, with stems covered with a thick 

 rind, usually marked below by the ring-like scars of fallen leaf-stalks, and 

 clothed above by their long-persistent sheaths ; occasionally stemless. Leaves 

 clustered at the top of the stem, plaited in the bud, fan-shaped or pinnate, 

 their rachises sometimes reduced to a narrow border, long-stalked, with petioles 

 dilated into clasping sheaths of tough fibres (vaginas)^ on fan-shaped leaves, 

 furnished at the apex on the upper side with a thickened concave body (llgule). 

 Flowers minute, perfect or unisexual, in the axils of small thin mostly decid- 

 uous bracts, in large compound clusters (spadix) surrounded by boat-shaped 

 bracts (sjyathes) ; sepals and petals free or more or less united ; stamens 

 usually 6 ; anthers 2-celled, introrse, opening longitudinally ; ovary 3-celled, 

 with a single ovule in each cell ; styles 13. Fruit a drupe or berry ; embryo 

 cylindrical in a cavity of the hard albumen near the circumference of the seed. 

 Of the 130 genera now usually recognized and chiefly inhabitants of the tropics, 

 seven have arborescent representatives in the United States. 



CONSPECTUS OF THE NORTH AMERICAN ARBORESCENT GENERA. 



Leaves fan-shaped. 

 Leaf-stalks unarmed. 



Calyx and corolla united into a short 6-lobed cup. 



Fruit white, drupaceous ; albumen even. 1. Thrinax. 



Fruit black, baccate ; albumen channeled. 2. Coccothrinax. 



Perianth of a distinct calyx and corolla. 



Filaments subulate, united below into a slender cup adnate to the base of the corolla ; 

 fruit baccate. 3. Sabal. 



Leaf -stalks armed with marginal spines. 



Filaments slender, free ; fruit baccate. ' 4. Washingtbnia. 



Filaments triangular, united into a cup adnate to the base of the corolla ; fruit dru- 

 paceous. 5. Serenoa. 

 Leaves pinnate. 



' Flower-clusters produced on the stem below the leaves ; fruit violet-blue. 



6. Roystonea. 

 Flower-clusters produced from among the leaves; fruit bright orange-scarlet. 



7. Pseudophoenix. 



