STAXDLEY TREES AXD SHRUBS OF MEXICO. 21 



Perianth segments in 2 series, calyx and corolla, rarely similar but then more 

 than 5. 

 Petals distinct, rarely coherent above but distinct below. 



2. POLYPETALAE. 

 Petals united below (at least at the base) or throughout. 



3. GAMOPETAXAE. 



Series 1. APETALAE. 



Ovary superior, almost superior, or naked. 



Perfect and pistillate flowers without a perianth. 

 Ovary with 2 or more cells. 



Ovary 2-celled, with 1 ovule in each cell ; styles 2. Leaves alternate, 



simple; flowers in catkins BETUIiACEAE. 



Ovary 3 or 4-celled. 



Ovary 3-celled ; styles 3. or 1 but with 3 or 6 stigmas ; fruit a 3-celletl 



capsx;le EUPHORBIACEAE. 



Ovary 4-celled ; styles 2 or 4. or a 2-lobed sessile stigma : fruit 4-celled. 



indehiscent. Leaves fleshy, terete BATIDACEAE. 



Ovary 1-celled. 



Leaves reduced to whorled scales. Fruit conelike CASUARINACEAE. 



Leaves not reduced to whorled scales. 

 Ovule 1 in each cell. 



Leaves opposite, stipulate ; stamen 1 : ovule pendulous. 



CHLORANTHACEAE. 

 Leaves alternate, or opposite and estipulate : stamens 2 to 16 : ovule 

 erect. 

 Fruit a drupe, covered with pale wax : seeds without endosperm ; 



leaves estipulate, dentate MYRICACEAE. 



Fruit a small berry ; seeds with endosperm ; leaves stipulate. 



entire. Flowers in long slender dense spikes PIPEEACEAE. 



Ovules more than 1 in each cell. Seeds with a tuft of hairs ; leaves 



stipulate SALICACEAE. 



Perfect and pistillate flows with a i)erianth. 

 A. Ovary 1. 1-celled. 

 B. Ovule 1. 



Leaves stipulate. 



Leaves deeply lobed. alternate ROSACEAE. 



Leaves simple. 



Styles 3. distinct or connate at the base. Stipules often sheath - 



like POLYaONACEAE. 



Style 1 and undivided, or bipartite, or of 1 or 2 sessile stigmas. 

 Flowers perfect, racemose. Leaves alternate. 



PHYTOLACCACEAE. 

 Flowers unisexual. 



Stamens more numerous than the perianth segments; stami- 



nate flowers with a perianth EUPHORBIACEAE. 



Stamens as many as the perianth segments or fewer : stami- 

 nate flowers sometimes without a perianth. Leaves alter- 

 ] nate. 



Flowers solitarj- or clustered : juice not milky_ULMACEAE. 

 Flowers spicate. racemose, or capitate ; juice milky. 



MORACEAE. 



