XXV 



23a. Leaves parallel-veined Ib, in ALISMACEAE, p. 3. 



23b. Leaves net-veined . Ib, in NYMPHAEACEAE, p. 35. 



24a. Leaves opposite or whorled 25. 

 24b. Leaves alternate 26. 



25a. Leaves less than 2 cm. long CALLITRICHACEAE, p. 68. 



25b. Leaves more ( than 2 cm. long Ib, in NAJAPACEAE, p. 2. 



26a. Leaves attached by the center to the stalk 



2b, in NYMPHAEACEAE, p. 35. 



26b. Leaves attached by the margin 27. 



27a. Leaves parallel-veined 28. 



7b. Leaves net-veined, with a single midvein; lanceolate or elliptical 

 in outline 29b, in POLYGONACEAE, p. 28. 



28a. Leaves not over 2 dm. long Ib, in NAJADACEAE, p. 2. 

 28b. Leaves very long and grass-like 14a, in GRAMINEAE, p. 5. 



29a. Brown, yellow, or white plants, without green color 30. 

 29b. Plants with normal green color, at least in some parts 33. 



30a. Stemless and* leafless plants, consisting of flowers only and 

 partly underground 4a, in ARACEAE, p. 8. 



30b. Stems climbing on other plants 



Ib, in CONYOLYULACEAE, p. 91. 



30c. Stem and flower-stalks erect, not climbing 31. 

 Sla. Corolla regular; stamens 612 la, in ERICACEAE, p. 84. 

 31b. Corolla irregular 32. 



32a. Sepals and petals each 3; flowers in simple racemes 



5a, in ORCHIDACEAE, p. 16. 

 32b. Sepals 5; corolla of united petals 



OROBANCHACEAE, p. 106. 



33a. Stem thick and fleshy, leafless, thorny CACTACEAE, p. 77. 



S3b. Stem not thorny 34. 



34a. Leaves none 35. 

 34b. Leaves reduced to small scales 40. 

 34c. Leaves thick and fleshy 44. 

 34d. Leaves hollow 45. 



34e. Leaves small, all basal, bearing large glandular hairs on the 

 upper surface DROSERACEAE, p. 48. 



35a. Stem none, the flowers appearing at or partially beneath the 

 surface of the soil 4a, in ARACEAE, p. 8. 



35b. Stem present 36. 



36a. Stem freely branched 2a, in LILIACEAE, p. 10. 



36b. Stem unbranched, except possibly in the flower-clusters 

 37. 



