Jones: Flora of Illinois 15 



purplish ; stems rigid and almost woody 



107. ClSTACEAE 



15. Sepals united at least below. 



20. Flowers surrounded by a calyx-like involucre, the calyx 

 blue or pink, corolla-like; stamens 3-5, exserted.... 



54. Nyctaginaceae 



20. Flowers not surrounded by an involucre; calyx green. 



21. Petals and stamens hypogynous 



58. Caryophyllaceae 



21. Stamens inserted on the calyx. 



22. Stigma capitate; style 1; petals present (absent 



in Peplis) ; fruit a capsule 



113. Lythraceae 



22. Stigmas 2, sessile or nearly so; petals none; fruit 



a utricle Scleranthus in 55. Illecebraceae 



3. Corolla sympetalous (petals united, at least below). 

 23. Corolla irregular (flowers zygomorphic). 



24. Fruit of 4 small nutlets; ovary 4-lobed; stem 4-angled; leaves usually gland- 

 ular-punctate; plant usually with mint odor 135. Labiatae 



24. Fruit a capsule; ovary not 4-lcbed; plants without mint odor. 



25. Seeds few, borne on hooks in the elastically dehiscent capsule 



142. Acanthaceae 



25. Seeds numerous, not borne on hooks; capsule not elastically dehiscent. 

 26. Ovary 1-loculed with 2 parietal placentae; corolla 3-5 cm. long, 

 gibbous, campanulate, 5-lobed and somewhat 2-lipped; capsule 

 10-15 cm. long, the beak longer than the body; odoriferous gland- 

 ular annuals 141. Martyniaceae 



26. Ovary 2-loculed; placentae axial 137. SCROPHULARIACEAE 



23. Corolla regular or nearly so (flowers actinomorphic). 

 27. Leaves in whorls. 



28. Flowers yellow; fruit a capsule 121. Primulaceae 



28. Flowers white or greenish. 



29. Flowers in umbels; corolla with 5 reflexed lobes; fruit a many-seeded 

 follicle; seeds with a tuft of silky hairs; plants with milky juice.... 



129. Asclepiadaceae 



29. Flowers axillary or cymose; corolla 4- (or 3-)lobed; fruit of 2 



united indehiscent 1 -seeded nutlets; sap watery 



1 45. RUBIACEAE 



27. Leaves not whorled. 



30. Leaves evergreen, opposite; stems trailing; flowers axillary; plants 

 glabrous. 

 31. Leaf-base narrowed; corolla blue, 5-lobed, 1.5-3 cm. long; calyx 



5-parted; stamens 5; stigma annular, its apex penicillate 



Vinca in 128. Apocynaceae 



31. Leaf-base rounded or cordate; corolla white or pink, usually 4-lobed, 



1-1.5 cm. long; calyx 4-toothed; stamens 4; stigmas 4; fruit a red 



or white double drupe Mitchella in 145. RuBlACEAE 



30. Leaves rarely evergreen; plants not as above in all respects . 



32. Leaves with stipules, or the petioles connected by a (sometimes bristle- 



bearing) stipular membrane or line. 

 33. Ovary inferior 145. RUBIACEAE 



33. Ovary superior 126. LoGANIACEAE 



32. Leaves without stipules. 



34. Ovaries 2, or if 1, deeply lobed; fruit usually of 2 follicles; seeds 



with a tuft of silky hairs; plants usually with milky juice. 



35. Flowers in cymes, or solitary 128. Apocynaceae 



35. Flowers in umbels 129. AscLEPIADACEAE 



34. Ovary 1 ; fruit a capsule or drupe; plants with watery juice. 



