674 RUTACEAE 



Gynoecium 2-carpellary : leaf-blades entire. 2. THAMNOSMA. 



** Ovules 2 in each cavity : capsule not lobed, 2-5 together. 



Calyx wanting. 3. XANTHOXYLUM. 



Calyx present. 4. FAGARA. 



b. Fruit indehiscent, samaroid. 



Filaments glabrous : fruit separating into 3-4 carpels which are winged on the 



back. . 5. HELIETTA. 



Filaments pubescent : fruit winged all around. 6. PTELEA. 



B. Fruit a pulpy drupe or a berry. 



Stamens 8 : fruit a drupe : leaf-blades 3-5-foliolate. 7. AMYRIS. 



Stamens 20-60 : fruit a berrv : leaf-blades 1-foliolate. 8. CITRUS. 



1. RUTA L. 



Perennial caulescent sometimes partly woody herbs, with glandular-punctate foliage 

 and often heavy scented herbage. Leaves alternate : blades divided. Flowers in terminal 

 corymbose or panicled cymes. Sepals 4-5, persistent. Petals 4-5, yellow or greenish, 

 imbricated. Disk thick, 8-10-lobed. Stamens 8-10. Ovary 4-5-celled, sessile, 4-5- 

 lobed : styles united : stigma terminal. Ovules several in each cavity of the ovary. 

 Capsule 4-5-celled, 4-5-lobed, commonly opening at the apex. Seeds several. 



1. Ruta graveolens L. Stems 2-8 dm. tall, corymbose at the ends : leaf-blades twice 

 ternately divided, the ultimate segments rounded or notched at the apex : sepals triangular 

 or ovate, 2.4-4 mm. long: petals 5-7 mm. long, the broad blade with involute margins and 

 apex, abruptly narrowed into the claw : capsules depressed, 8-11 mm. wide, 4-5-lobed. 



In waste places and cultivated grounds, eastern United States. Native of Europe. Spring to fall. 



2. THAMNOSMA Torr. & Frem. 



Strong-scented shrubs or shrubby herbs, usually densely glandular. Leaves alternate : 

 blades simple, narrow, entire, often reduced to scales. Flowers perfect, regular, in racemes 

 or racemose cymes. Sepals 4. Petals 4, yellow or purplish, sessile, often erect. Disk 

 cup-like, entire or crenate. Stamens 8 : filaments subulate or filiform. Ovary 2-celled, 

 2-lobed, long-stalked or nearly sessile : styles united : stigma capitate. Ovules 5-6 in each 

 cavity. Capsule leathery, 2-celled, 2-lobed, opening at the apex. Seeds 4-6, nearly reni- 

 form. Testa crustaceous, smooth or rough. Embryo curved. 



1. Thamnosma Texaiia (A. Gray) Torr. A low partially herbaceous shrub, 1-5 dm. 

 tall. Stems much branched, wiry, often densely glandular : leaf-blades linear or linear- 

 oblong, 5-10 mm. long, obtuse, more or less glandular-punctate, entire, sessile or nearly so, 

 early deciduous : flowers in terminal interrupted racemes : pedicels 1-2 mm. long : calyx 

 about 2 mm. broad : sepals ovate, obtuse : petals yellow or purplish, elliptic, oblong-ellip- 

 tic or oval, 2.5-3 mm. long, obtuse, slightly involute : stamens shorter than the petals : 

 filaments glabrous, subulate : capsules short-stalked, 5-6 mm. high, 2-lobed, the valves ex- 

 tending to the middle : seeds nearly 2 mm. broad, flattened, tuberculate. 



On plains and prairies, Texas to New Mexico and Mexico. Spring to fall. 



3. XANTHOXYLUM 1 L. 



Aromatic, often prickly, shrubs or trees, with relatively smooth stems. Leaves alter- 

 nate : blades pinnately compound : leaflets with more or less pellucid-punctate, entire or 

 toothed blades. Flowers greenish yellow, polygamous, in axillary cymes. Sepals want- 

 ing. Petals 4-5. Stamens 4-5, abortive in pistillate flowers. Carpels 1-5, short-stalked, 

 1-celled, oblique : styles distinct, or united above. Ovules 2 in each cavity. Capsular 

 fruit a single carpel or 2-5 carpels together, not lobed, glandular-punctate, 2-valved. 

 Seed solitary, finally exserted. 



1. Xanthoxylum Americanum Mill. A prickly aromatic shrub, with spreading 

 branches. Leaf-blades pinnately-compound, 1-3 dm. long, the rachis nearly terete : leaf- 

 lets ovate or oblong or rarely oval, 4-8 cm. long, obtuse or short-acuminate, deep green 

 above, paler and more or less pubescent beneath, crenate with flat-topped teeth, sessile or 

 short -petioled : calyx wanting : flowers in sessile clustered cymes on the wood of the pre- 

 vious season, slender-pedicelled : corolla yellowish and greenish, 3-3.5 mm. broad : cap- 

 sules globose or ellipsoidal, 5 mm. in diameter, wrinkled and glandular-punctate : seeds 

 ovoid, 4 mm. long, black, shining. 



On river banks and in woods, Quebec and Ontario to Minnesota, Georgia, Missouri and Nebraska. 

 Spring. PRICKLY ASH. TOOTHACHE-TREE. 



1 Originally spelled ZANTHOXYLUM. 



