46 THE INDIANA WKF.D BOOK. 



KEY TO THE DIVISIONS OF EXOGENS. 



a. Petals wholly wanting; calyx present, except in some spurges. 



APETALOUS EXOGENS. p. 4(1 

 aa. Petals and sepals both present. 



fc. Petals all separate and distinct one from another, except hi the 

 pea family where the lower two are often united. (Figs. 9; 



10, a.) POLYPETALOUS EXOGENS. ]). 4<>. 



T)b. Petals more or less united into one piece. (Fig. 10. b-y.) 



GAMOPETALOUS EXOGENS, p. 47. 



KEY TO THE FAMILIES OF APETALOUS EXOGEN WEEDS. 



. Fruit an achene, 1-celled, 1 -seeded ; ovary 1 only, superior. (Nettles. 



docks, smartweeds, etc.) 



&. Herbs with small clustered greenish flowers, and, in our weeds, with 

 stinging hairs; stipules not forming a circular sheath about 

 the joints ; achenes compressed, ovate or oblong. 



NETTLE FAMILY, p. 61. 



II). Herbs without stinging hairs but usually with a sour or very acrid 

 juice; stipules forming a cylindrical sheath about the joints of 

 stem ; achenes 3-sided or 3-angled. BUCKWHEAT FAMILY, p. 03. 

 era. Fruit not an achene; ovary 1 only, superior. (Lamb's quarters, pig- 

 weeds, pokewiCHl, spurges, etc.) 

 c. Leaves without milky juice; fruit not 3-seeded. 



d. Leaves not in whorls; fruit not a capsule; stem usually erect 



e. Fruit a utricle. 1-celled, 1-seeded (Fig. 14. d, c.) ; stipules none. 



/. Flowers not surrounded by dry pointed bracts; sepals 



green or greenish ; leaves and stems usually white-mealy 



or glandular. GOOSEFOOT FAMILY, p. 69. 



//. Flowers each surrounded by 3 dry persistent awl-shaped 



bracts; sepals brown or colorless; plant not mealy or 



glandular. AMARANTH FAMILY, p. 72. 



ce. Fruit a fleshy 10-seeded berry ; styles and stamens 10 each ; 



ovary 10-celled ; flowers numerous in terminal racemes ; 



leaves alternate, entire. POKEWEED FAMILY, p. 75. 



(Id. Leaves in whorls of 5's or G's ; stem prostrate, spreading; fruit 



a 3-celled capsule. CARPET-WEED FAMILY', p. 76. 



rr. Leaves with a milky acrid juice ; staniinate and pistillate flowers 



of our weeds separate but on the same plant, the pistillate ones 



enclosed by a cup-shaped involucre or a leaf-like bract; fruit 



3-seeded. SPURGE FAMILY, p. 91. 



KEY TO THE FAMILIES OF POLYPETALOUS EXOGEN WEEDS. 



a. Stem leaves opposite, entire. 



ft. Leaves not punctuate with pelluci'd and dark dots ; stamens not 



over 10, separate; ovules borne on a central column; corolla 



not yellow. PINK FAMILY, p. 77. 



&&. Leaves and petals with numerous very small round pellucid or dark 



. dots; stamens very numerous united in 3 or more sets; ovules 



borne on the walls of the ovary ; corolla yellow. 



ST. JO?IN'SWORT FAMILY, p. OS. 



