KEY TO THE FAMILIES AND GENERA 



119 



mm. Plant unarmed or with sting- 

 ing hairs, 

 i. Styles free or united only at 



base. 



j. Anther-cells spherical to 

 oblong. 



K. Anthers 2-celled 27. Afallotua. 



KK. Anthers 3-4-celled : Ivs. 



usually peltate 28, Macaranya. 



jj. Anther-cells elongated, 



often vermiform 29. Acalypha. 



n. Styles united above the 



base: st. often climbing, 

 j. Infl. without conspicuous 



involucre. 



K. Number of stamens 

 usually 3; styles free 



at apex 30. Tragia. 



KK. Number of stamens 

 8-30; styles united 

 to the apex into a 



swollen column 31. Plukenetia. 



jj. Infl. subtended by a con- 

 spicuous involucre 32. Dalecham- 



DD. Juice almost always more or less milky [p*. 



(chief exceptions in Cluytia and 

 relatives). 

 E. The fls. with petals, at least the 



staminate. 

 F. Calyx valvate. 



o. Lvs. simple, palmate 33. Aleurites. 



oo. Lvs. compound 34, Joannesia. 



IT. Calyx imbricate. 



G. Petals free from one another. 

 H. The stamens in 2 or more 



whorls. 



I. Number of stamens about 

 10: Ivs. usually palmately 



veined 35. Jatropha. 



ii. Number of stamens 15-30 

 or more : Ivs. pinnately 



veined: styles entire 36. Codixum. 



HH. The stamens in 1 whorl, 



usually about 3-5 37. Cluytia. 



GO. Petals connate: Ivs. usually 



palmately veined. 

 H. Some of the filaments united: 



Ivs. simple 35. Jatropha. 



HH. Filaments free:l vs. compound.38. Ricinoden- 

 EE. The fls. apetalous. [dron. 



p. Sepals valvate or slightly im- 

 bricate in some. 



o. Lvs. trifoliate 39. Hevea. 



GO. Lvs. simple, pinnately veined. 

 H. Number of stamens 3: Ivs. 



spiny margined 40. Pachy- 



HH. Number of stamens 1: Ivs. not [stroma. 



spiny 41. Ophthal- 



FF. Sepals or lobes of calyx, if any, im- [moblapton. 



bricate: Ivs. simple. 

 a. Number of stamens usually 10 or 



more (5-50 J. 



H. Staminate calyx with 5 sepals 

 connate, at least at base: 

 Ivs. usually palmately 

 veined: st. erect. 



i. Herbage with stinging hairs. 35. Jatropha. 

 n. Herbage usually glabrous. . .42. Manihot. 

 HH. Staminate calyx 3-5-lobed: 

 Ivs. pinnately veined: st. 



climbing or trailing 43. Afabea. 



H. Staminate calyx of 1 or 2 



sepals 44. Homalan- 



H. Staminate calyx cupulate, [thus. 



truncate or dentate: Ivs. 



broad, hairy 45, Hura. 



GQ. Number of stamens 1-5. 



H. Staminate calyx with 4-5 free 



sepals: st. climbing 46. Omphalia. 



HH. Staminate calyx with 2-3 

 sepals, free or connate at 

 base, 

 i. Infl. usually terminal: seed 



carunculate 47. Sebastiana. 



11. Infl. usually axillary: seed 



not carunculate 48. Exaecaria. 



HHH. Staminate calyx with con- 

 nate sepals, 1-3-lobed. 

 I. The stamens 2-3. 

 j. Stamens free. 



K. Base of caps, persistent 



as a pointed piece. . .49. Sapium. 

 KK. Base of caps, not per- 

 sistent, only a 3- 

 parted central 

 column remaining. . .50. Stiltingia. 

 jj. Stamens united. 



K. Pistil 4-celled 51. Maprounia. 



KK. Pistil G-9-celled 52. Hippomane. 



ii. The stamens 1 



j. Infl. terminal 51. Maprounia. 



jj. Infl. lateral or axillary. . .41. Ophthal- 

 HIIHH. Staminate calyx 0, or rarely [moblapton. 



1-2 minute scales 53. CoUiguaya, 



BB, Fls. in c:yathia (see explanation under 



Euphorbia). 

 c. Cyathia regular or nearly so. 



o. Involucral glands free from one 

 another, alternate with lobes of 



involucre 54. Euphorbia. 



DD. Involucral glands united into a ring 



around the lobes 55. Synadenium. 



cc. Cyattua decidedly irregular 56. Pedilanthut. 



172. BUXACE-E. 



A. Cells of ovary with 2 ovules each; stamena 4. 

 B. Lvs. alternate. 



c. Evergreen shrubs: Ivs. entire 1. Sarcococca. 



cc. Evergreen herbs: Ivs. dentate 2. Pachys- 



\andra. 



BB. Lvs. opposite 3. Buxua. 



A A. Cells of ovary with 1 ovule each; stamens 



numerous: Ivs. opposite 4. Simmond- 



(sia. 



173. BETULACE^;. 



A. Staminate fls. with 4 perianth-segms. or by 

 abortion fewer (Birch Tribe). 



B. Stamens 2 1. Betula. 



BB. Stamens 4 2. Alnits. 



AA. Staminate fls. with no perianth (Hazel Tribe). 



B. Nut large, inclosed by a leafy involucre: 



staminate fls. with 2 bractlets; pistillate 



fls. 2-4, capitate 3. Corylut. 



BB. Nut small, subtended by or inclosed in a 

 large bractlet: staminate fls. with no 

 bractlets; pistillate catkins spike-like. 

 c. Fruiting bractlet flat, 3-cleft and incised. . 4. Carpinus. 

 cc. Fruiting bractlet bladder-like, closed* 



membranous 5. Ostrya, 



174. FAGACE-ffi. 



A. Ovary of pistillate fls. 6-celled ; spikes of either 

 sex erect and strict: fruiting involucre or bur 



densely covered with strong pickles 1. Castanea. 



AA. Ovary of pistillate fls. 3-celled, rarely 4- or 5- 



celled in some species of Quercus. 

 B. Staminate fls. 1-3 in a cluster: Ivs. usually 



small 2. Nothofagu*. 



BB. Staminate fls. in loose, roundish pendulous 



heads: Ivs. generally large 3. Fagus. 



BBS. Staminate fla in pendulous catkins or the 



spikes of either sex erect and strict. 

 c. Involucre of numerous scales forming 



a cup in f r. and subtending the acorn. ... 4. Quercus. 

 cc. Involucre in fr. armed with clusters of 

 prickles or tubercles, wholly including 

 the fr. f perfectly closed or at length 

 split irregularly 5. Castanopsis 



175. SALICACE-ffi. 



A. Lvs. usually narrow: disk composed of 1 or 2 

 glands which are distinct or barely connate 



at base 1. Salix. 



AA. Lvs. usually broad: disk cyathiform, often 



oblique or cup-shaped, entire or lobed.. . . 2. Populus. 



176. EMPETRACE^B. 



A. Fls. axillary, solitary; stamens 3; pistil 6-9- 



merous 1. Empetrum. 



AA. Fls. axillary in -'* '"' 3's; stamens 2; pistil 



2-merous 2. Ceratiola. 



AAA. Fls. subcapitate; stamens usually 3; pistil 3- 



merous 3. Corema. 



177. GINKGOACE^E. 



Ovule-bearing blade, long-stalked, shortly 2-co 

 cut at apex, the lobes dilated into a ring or 

 short cup adnate to the seed: anther-cells 2, 

 pendulous: Ivs. fan-shaped Ginkgo. 



