Part 2

39. Halorageae (p. 180). Aquatic or marsh herbs; flowers perfect or polygamo-dioecious, small, axillary or spicate; petals often none. Stamens 1--8. Ovary inferior, the calyx-limb obsolete or very short. Fruit small, indehiscent, 1--4-celled, 1--4-seeded. Leaves alternate or opposite, the submersed often dissected.

[*] 2. Ovary inferior (except in Lythraceae), 1--several-celled; style entire; flowers perfect, regular or nearly so, mostly 4-merous; herbs, with simple and mostly entire leaves without stipules.

40. Melastomaceae (p. 183). Calyx open. Stamens definite; anthers opening by an apical pore. Leaves opposite, 3--7-nerved; flowers cymose.

41. Lythraceae (p. 184). Calyx-lobes valvate. Pod free, but enclosed in the calyx, membranous, 1--4-celled, many-seeded with axile placentae. Leaves mostly opposite; flowers axillary or whorled; petals crumpled, or none.

42. Onagraceae (p. 186). Calyx-lobes valvate. Ovary 1--4-celled, the cells 1--many-ovuled. Stamens 2, 4, or 8. Petals 2 or 4, convolute, or none. Leaves opposite or alternate.

[*] 3. Ovary inferior (except in Passifloraceae and Ficoideae), 1-celled with parietal placentae or several-celled by the intrusion of the placentae; flowers regular, perfect or unisexual; styles free or united; herbs.

[+] Embryo straight; cotyledons foliaceous; leaves alternate, often lobed.

43. Loasaceae (p. 193). Flowers perfect. Stamens indefinite. Style entire or 2--3-cleft. Capsule 1-celled, with 2 or 3 many-seeded placentae. Pubescence of hooked hairs.

44. Passifloraceae (p. 194). Climbing by tendrils. Flowers perfect. Stamens 5, monadelphous. Ovary stalked, superior, becoming a 1-celled many-seeded berry with 3 or 4 placentae. Styles 3, clavate.

45. Cucurbitaceae (p. 194). Tendril-bearing vines, with dioecious or monoecious flowers. Corolla 5-lobed, often confluent with the calyx. Stamens 3 or 5, usually more or less united and the anthers often tortuous. Fruit fleshy or membranous, 1--5-celled, the placentae often produced to the axis and revolute. Seeds exalbuminous.

[+][+] Embryo curved or coiled about central albumen; leaves entire.

46. Cactaceae (p. 196). Fleshy and mostly leafless prickly plants, with solitary sessile perfect flowers. Calyx-lobes and petals indefinite, imbricated, the numerous stamens on the tube. Fruit a 1-celled many-seeded berry.

47. Ficoideae (p. 198). Calyx-lobes or sepals 5 and petals none in our genera. Capsule 3--5-celled with axile placentae, loculicidal or circumscissile, many-seeded. Often fleshy; leaves mostly opposite or verticillate.

[*] 4. Flowers small, regular, perfect or polygamous; calyx-limb minute or obsolete; ovary inferior, 2--several-celled, with solitary pendulous ovules; petals and stamens mostly 4 or 5, on the margin of an epigynous disk surrounding the styles; albumen copious.

48. Umbelliferae (p. 198). Flowers in umbels or heads. Petals (inflexed) and stamens 5. Styles 2. Fruit of 2 dry seed-like carpels, the pericarp usually with oil-tubes. Herbs, with alternate mostly compound leaves.

49. Araliaceae (p. 212). Flowers mostly in umbels and nearly as in Umbelliferae; petals not inflexed and styles 2 or more. Fruit a 2--several-celled drupe. Herbs or shrubs, with alternate mostly compound leaves.

50. Cornaceae (p. 213). Flowers not in umbels; petals (valvate, or none) and stamens 4 or 5. Style 1. Fruit a 1--2-seeded drupe. Trees, shrubs, or rarely herbs, with opposite or alternate simple and mostly entire leaves.

DIVISION II. GAMOPETALOUS: calyx and corolla both present, the latter of united petals (excepting some Ericaceae, Styracaceae, and Oleaceae, Galax, Statice, and Lysimachia). Apetalous flowers occur in Glaux and some Oleaceae. Stipules present only in Rubiaceae and Loganiaceae, or rarely in Caprifoliaceae.

[*] 1. Ovary inferior; stamens borne upon the corolla, alternate with its lobes.

[+] Stamens distinct; leaves opposite or whorled; seed albuminous except in Valerianaceae.

51. Caprifoliaceae (p. 216). Corolla mostly 5-lobed, regular or irregular, the stamens as many (one fewer in Linnaea, doubled in Adoxa). Ovary 1--several-celled; fruit a berry, drupe, or pod, 1--several-seeded. Shrubs or herbs; leaves opposite, rarely stipular, not turning black in drying.

52. Rubiaceae (p. 222). Flowers regular, 4--5-merous, the corolla mostly valvate. Ovary 2--4-celled. Herbs or shrubs; leaves simple, entire, opposite with stipules, or verticillate, usually turning black in drying.

53. Valerianaceae (p. 228). Stamens (1--4) fewer than the lobes of the somewhat irregular corolla. Ovary with two abortive or empty cells and one containing a suspended ovule. Fruit dry and indehiscent. Herbs.

54. Dipsaceae (p. 229). Flowers mostly 4-merous and with 4 (rarely 2) stamens, involucellate in involucrate heads; corolla-lobes imbricate. Ovary simple, 1-celled, with a suspended ovule. Herbs.

[+][+] Anthers connate into a tube.

55. Compositae (p. 230). Stamens as many as the valvate corolla-lobes. Ovary with a solitary erect ovule, becoming an achene. Albumen none. Calyx-limb reduced to a pappus or none. Flowers in involucrate heads.

[*] 2. Ovary inferior (or superior in most Ericaceae and in Diapensiaceae); stamens free from the corolla or nearly so (adnate in some Diapensiaceae), as many as the lobes and alternate with them, or twice as many; leaves alternate (opposite in some Ericaceae); style 1.

[+] Juice milky; capsule 2--5-celled, many-seeded; herbs.

56. Lobeliaceae (p. 305). Corolla irregular, 5-lobed. Stamens united, at least by the anthers. Capsule 2-celled or with two placentae.

57. Campanulaceae (p. 307). Corolla regular, 5-lobed, valvate. Stamens usually distinct. Capsule 2--several-celled.

[+][+] Juice not milky nor acrid; capsule 3--10-celled.

58. Ericaceae (p. 309). Flowers mostly regular, 4--5-merous. Stamens distinct, more usually twice as many as the corolla-lobes or petals. Ovary inferior or superior. Herbs or shrubs.

59. Diapensiaceae (p. 326). Flowers regular. Stamens 5, on the corolla, or monadelphous with 5 petaloid staminodia. Ovary superior, 3-celled.

[*] 3. Ovary superior; stamens as many as the corolla-lobes and opposite them.

60. Plumbaginaceae (p. 327). Stamens 5, on the base of the petals. Styles 5. Fruit an achene or 1-seeded utricle. Herbs; leaves radical.

61. Primulaceae (p. 328). Stamens 4--8, perigynous. Style 1. Fruit a capsule with several seeds on a central placenta. Herbs; leaves radical or opposite or alternate.

62. Sapotaceae (p. 332). Flowers small, 4--5-merous. Style 1. Ovary few--several-celled; fruit fleshy, bearing a single bony-coated seed. Shrubs or trees, with milky juice and alternate entire leaves.

[*] 4. Ovary superior or more or less adnate to the calyx, few--several-celled, the cells 1-ovuled; stamens twice as many as the corolla-lobes or more; trees or shrubs, with alternate leaves.

63. Ebenaceae (p. 333). Flowers dioecious or polygamous. Stamens on the corolla. Ovary superior. Styles distinct. Fruit fleshy, few-seeded.

64. Styracaceae (p. 333). Flowers perfect. Stamens subhypogynous. Ovary more or less inferior. Style 1. Fruit dry or nearly so, 1--4-seeded.

[*] 5. Ovary superior, of two carpels (sometimes by division apparently 4-carpellary, sometimes of 3--5 in Polemoniaceae, Convolvulaceae, and Solanaceae); stamens on the corolla (except in apetalous Oleaceae), alternate with its lobes, as many or fewer.

[+] Corolla not scarious and nerveless.

[++] Corolla none, or regular and 4-cleft or -parted, the stamens fewer than its lobes; style 1; seeds 1--3.

65. Oleaceae (p. 335). Trees or shrubs, with opposite and pinnate or simple leaves. Flowers perfect or polygamo-dioecious. Stamens mostly 2, alternate with the usually 2-ovuled carpels.

[++][++] Corolla regular, its lobes 4--5 or rarely more; stamens as many.

[=] Ovaries 2, becoming follicles; stigmas and sometimes the styles united; herbs with milky juice, perfect 5-merous flowers, and simple entire leaves.

66. Apocynaceae (p. 337). Stamens distinct or the anthers merely connivent, with ordinary pollen. Style 1.

67. Asclepiadaceae (p. 338). Stamens monadelphous, the anthers permanently attached to a large stigmatic body; pollen mostly in waxy masses. Styles distinct below the stigma.

[=][=] Ovary compound (ovaries two in Dichondra), with 2 or 3 (rarely 4 or 5) cells or placentae; stamens distinct; mostly herbs.

[a.] Leaves opposite; corolla-lobes 4 or 5 or more.

68. Loganiaceae (p. 345). Leaves entire, with stipules or a stipular line joining their bases. Capsule 2-celled, few--many-seeded. Herbs or woody twiners (our species).

69. Gentianaceae (p. 346). Glabrous herbs; leaves entire, sessile and simple (except in Menyanthes). Capsule 1-celled with 2 parietal placentae or the whole inner surface ovuliferous, many-seeded.

[b.] Leaves alternate (sometimes opposite in Polemoniaceae and Hydrophyllaceae); corolla-lobes always 5 in our species.

70. Polemoniaceae (p. 354). Capsule usually 3-celled, loculicidal; seeds 1--many in each cell on the stout placental axis. Style 3-cleft or -lobed. Leaves opposite or alternate, simple or compound.

71. Hydrophyllaceae (p. 357). Leaves often lobed or divided, and the inflorescence frequently scorpioid. Style 2-parted or 2-lobed. Capsule 1-celled, 2-valved with two parietal or introflexed placentae, or sometimes 2-celled. Seeds 2 or more on each placenta.

72. Borraginaceae (p. 360). Leaves mostly entire and plants often rough-hispid; inflorescence commonly scorpioid. Style 1. Ovary 4-ovulate, usually 4-lobed and maturing as 4 separate or separable nutlets, or not lobed, 2--4-celled and separating when ripe into 2 or 4 nutlets.

73. Convolvulaceae (p. 367). Usually twining or trailing; flowers on axillary peduncles or cymose-glomerate. Corolla 5-lobed or 5-plaited, twisted in the bud. Styles 1 or 2. Ovary 2- (sometimes 3- or spuriously 4-) celled, becoming a globular 4--6-seeded capsule (or ovaries two and distinct in Dichondra). Cotyledons broad-foliaceous.

74. Solanaceae (p. 373). Style 1. Ovary 2-celled (rarely 3--5-celled), with numerous ovules on axillary placentae, becoming a pod or berry. Cotyledons narrow.

[++][++][++] Corolla more or less bilabiately irregular (sometimes nearly regular), 5-lobed. Fertile stamens 4 and didynamous, or 2. Style 1. Ovary always of two carpels.

[a.] Ovules several or many.

75. Scrophulariaceae (p. 377). Capsule 2-celled, with central placentae. Seeds small, usually numerous. Herbs; leaves alternate or opposite.

76. Orobanchaceae (p. 393). Root-parasites with no green foliage. Capsule 1-celled, with 2 simple or double parietal placentae. Seeds many.

77. Lentibulariaceae (p. 395). Aquatic or marsh herbs, with scapes or scape-like peduncles, sometimes nearly leafless. Corolla personate and spurred. Capsule globular, 1-celled; placentae central, free, many-seeded.

78. Bignoniaceae (p. 398). Large-flowered trees or often climbing shrubs, with usually opposite simple or compound leaves. Capsule 2-celled by a partition between the 2 parietal placentae. Seeds numerous, large, mostly winged.

79. Pedaliaceae (p. 399). Herbs, with opposite simple leaves. Ovary 1-celled with two bilamellar parietal placentae, or 2--4-celled by their union, becoming drupaceous or capsular. Seeds few or many, wingless.

80. Acanthaceae (p. 399). Herbs, with opposite simple leaves. Capsule 2-celled, loculicidal, with each axile placenta bearing 2--10 flattish seeds.

[b.] Cells of the ovary 1--2-ovuled; herbs or low shrubs, with opposite leaves.

81. Verbenaceae (p. 401). Ovary 2--4-celled, not lobed, the dry or drupaceous fruit separating into 2 or 4 1-seeded nutlets (fruit 1-celled and 1-seeded in Phryma). Style terminal.

82. Labiatae (p. 403). Ovary deeply 4-lobed around the style, the lobes becoming dry seed-like nutlets. Stems square; aromatic.

[+][+] Corolla scarious and nerveless; flowers regular, 4-merous; style 1.

83. Plantaginaceae (p. 422). Scapose herbs, with perfect or polygamo-dioecious or monoecious flowers in 1--many-flowered spikes. Fruit a circumscissile 2-celled capsule, with one or more peltate seeds in each cell, or an achene.

DIVISION III. APETALOUS EXOGENS. The corolla wanting (except in some Euphorbiaceae), and sometimes also the calyx.

[*] 1. Ovary superior (though sometimes enclosed within the calyx), 1-celled with a solitary basal ovule (several-celled in Phytolaccaceae); embryo coiled or curved (nearly straight in Polygonaceae) in or about mealy albumen (albumen none in some Chenopodiaceae); herbs.

[+] Fruit the hardened or membranous closed base of the corolla-like perianth enclosing a utricle.

84. Nyctaginaceae (p. 425). Perianth tubular or funnelform. Stamens hypogynous. Fruit ribbed or winged. Leaves opposite; stipules none.

[+][+] Fruit a utricle; perianth mostly persistent, small, 4--5-lobed or -parted, or none.

85. Illecebraceae (p. 426). Perianth herbaceous. Stamens perigynous. Leaves opposite; stipules scarious (none in Scleranthus).

86. Amarantaceae (p. 427). Flowers sessile, bracteate, the bracts (usually 3) more or less dry and scarious, as well as the 3--5 distinct sepals. Stamens 1--5, hypogynous. Utricle indehiscent or circumscissile. Embryo annular. Leaves mostly alternate, entire; stipules none.

87. Chenopodiaceae (p. 430). Flowers sessile, not scarious-bracteate. Sepals greenish or succulent, 5 or fewer, or none. Stamens 5 or fewer, perigynous or hypogynous. Embryo annular or spiral or conduplicate. Leaves alternate; stipules none.

[+][+][+] Ovary of several 1-ovuled carpels, in fruit a berry (in our genera).

88. Phytolaccaceae (p. 435). Sepals 4--5, petaloid or herbaceous. Stamens 5--30, hypogynous. Carpels 5--12. Embryo annular. Leaves alternate, entire; stipules none.

[+][+][+][+] Fruit a triangular or lenticular achene.

89. Polygonaceae (p. 436). Flowers on jointed pedicels. Calyx 3--6-lobed or -parted, more or less corolla-like. Stamens 4--12, on the calyx. Embryo nearly straight. Leaves alternate, with sheathing stipules or none.

[*] 2. Ovary compound, the cells many-ovuled (or 1-ovuled in Piperaceae); embryo minute in copious albumen; flowers perfect.

90. Podostemaceae (p. 444). Aquatic, with the aspect of sea-weeds or mosses, with minute naked flowers from a spathe-like involucre. Ovary superior; pod 2--3-celled.

91. Aristolochiaceae (p. 444). Terrestrial herbs or climbing shrubs. Calyx valvate, adnate at least at base to the 6-celled many-seeded ovary. Stamens 6--12, more or less united with the style. Leaves alternate, mostly cordate; stipules none.

92. Piperaceae (Sec. Saurureae), (p. 446). Marsh herb (our species). Perianth none. Carpels 3--4, distinct, with usually a single ascending seed. Leaves alternate, entire.

[*] 3. Ovary superior, simple, 1-celled, 1-ovuled, forming a berry or drupe; trees or shrubs, with mostly entire leaves and no stipules.

93. Lauraceae (p. 446). Flowers perfect or dioecious. Sepals 4 or 6, in 2 rows. Stamens 9--12; anthers opening by 2 or 4 uplifted valves. Seed suspended; albumen none. Aromatic; leaves alternate.

94. Thymelaeaceae (p. 448). Flowers perfect. Calyx corolla-like, 4--5-cleft. Stamens twice as many. Seed suspended, with little or no albumen. Acrid shrubs with very tough bark; leaves alternate.

95. Elaeagnaceae (p. 448). Flowers mostly dioecious. Calyx-tube becoming berry-like and enclosing the achene. Seed erect, albuminous. Leaves silvery-scurfy, opposite.

[*] 4. Ovary inferior, 1-celled, 1--3-ovuled (but 1-seeded); albumen without testa, bearing the embryo in a cavity at the apex; calyx-lobes valvate.

96. Loranthaceae (p. 449). Parasitic on trees, with jointed stems and opposite leaves. Flowers dioecious. Ovule solitary, erect. Fruit a berry.

97. Santalaceae (p. 450). Flowers perfect. Ovules 2--4, suspended from the apex of a central placenta. Fruit dry, indehiscent. Leaves alternate.

[*] 5. Flowers all unisexual (polygamous in some Urticaceae and Empetraceae, apparently perfect in Euphorbia); cells 1--2-ovuled; embryo nearly as long as the albumen or filling the seed; calyx often wanting, corolla-like only in some Euphorbiaceae and Empetraceae; stipules often present.

[+] 1. Ovary superior, 3-celled (1-celled in Crotonopsis) with 1 or 2 pendulous ovules in each cell; herbs.

98. Euphorbiaceae (p. 451). Flowers monoecious or dioecious (involucrate and apparently perfect in Euphorbia). Mostly with milky juice, and usually alternate often stipulate leaves.

[+] 2. Ovary 1-celled, 1-seeded; trees or shrubs (except some Urticaceae).

[++] Calyx regular, the stamens as many as the lobes and opposite them or fewer; ovary superior.

99. Urticaceae (p. 461). Flowers monoecious, dioecious, or (in Ulmeae) perfect. Seeds exalbuminous or nearly so. Inflorescence very various.

[++][++] Perianth mostly none; at least the staminate flowers in aments or spikes or dense heads; albumen none.

100. Platanaceae (p. 466). Trees, with alternate palmately lobed leaves, sheathing stipules, and monoecious flowers in separate globose heads. Ovary superior; fruit a club-shaped nutlet.

101. Juglandaceae (p. 467). Trees, with alternate pinnate leaves, no stipules, and monoecious flowers, the staminate in aments. Ovary inferior; fruit a nut.

102. Myricaceae (p. 469). Shrubs, with resinous-dotted leaves, with or without stipules, and monoecious or dioecious flowers, both kinds in short scaly aments. Ovary superior, becoming a small drupe-like nut.

[+] 3. Ovary 2--7-celled, with 1 or 2 suspended ovules in each cell, becoming 1-celled and 1-seeded; calyx mostly none or adherent to the ovary; trees or shrubs with simple leaves.

103. Cupuliferae (p. 470). Flowers monoecious. Fruit a nut surrounded by an involucre, or (in Betuleae) a small winged or angled naked nutlet in the axils of the scales of an ament.

[+] 4. Ovary 1-celled, becoming a 2-valved pod with two parietal or basal placentae bearing numerous small comose seeds; perianth none.

104. Salicaceae (p. 480). Dioecious trees or shrubs, with both kinds of flowers in aments, and simple alternate stipulate leaves.

[+] 5. Ovary several-celled, becoming a drupe containing 3--9 1-seeded nutlets; seed erect; low shrubby heath-like evergreens.

105. Empetraceae (p. 487). Flowers polygamous or dioecious, scaly-bracted. Sepals somewhat petaloid or none. Embryo axile in copious albumen.

[+] 6. Ovary 1-celled with a suspended ovule, becoming an achene; calyx none; aquatic herbs, with finely dissected whorled leaves.

106. Ceratophyllaceae (p. 488). Flowers monoecious, minute, axillary and sessile. Albumen none; the seed filled with a highly developed embryo.

SUBCLASS II. GYMNOSPERMOUS EXOGENS. Ovules naked upon a scale, bract, or disk. Cotyledons two or more.

107. Coniferae (p. 489). Resiniferous trees or shrubs, with mostly awl-shaped or needle-shaped and evergreen leaves, and monoecious or dioecious flowers.

CLASS II. MONOCOTYLEDONOUS PLANTS.

Stems without central pith or annular layers, but having the woody fibres distributed irregularly through them (a transverse slice showing the fibres as dots scattered through the cellular tissue). Embryo with a single cotyledon and the early leaves always alternate. Parts of the flower usually in threes (never in fives), and the leaves mostly parallel-veined. Our species herbaceous, excepting Smilax.

[*] Ovary inferior (superior in Bromeliaceae, nearly so in some Hemodoraceae); at least the inner lobes of the perianth petal-like.

[+] 1. Seeds without albumen, very numerous and minute.

108. Hydrocharidaceae (p. 495). Aquatics, with dioecious or polygamous flowers from a spathe; outer perianth calyx-like, the inner sometimes wanting. Stamens 3--12. Ovary 1-celled with 3 parietal placentae or 6--9-celled with axile placentae.

109. Burmanniaceae (p. 496). Terrestrial, with scale-like cauline leaves and regular perfect triandrous flowers. Perianth corolla-like.

110. Orchidaceae (p. 497). Terrestrial, with very irregular perfect flowers. Stamens and style connate; anthers 1 or 2. Capsule 1-celled; placentae 3, parietal. Perianth corolla-like.

[+] 2. Seeds albuminous. (Ovary 3-celled and flowers regular in our genera.)

111. Bromeliaceae (p. 511). Mostly epiphytes, with dry persistent scurfy leaves. Flowers 6-androus; outer perianth calyx-like.

112. Hemodoraceae (p. 512). Fibrous-rooted, with equitant leaves and perfect 3- or 6-androus flowers. Perianth persistent, woolly or scurfy outside. (Ovary sometimes nearly free; leaves flat in Aletris.)

113. Iridaceae (p. 513). Root not bulbous; leaves equitant in two ranks. Flowers from a spathe. Stamens 3, opposite the outer lobes of the corolla-like perianth; anthers extrorse.

114. Amaryllidaceae (p. 515). Often bulbous-rooted and scapose. Perianth corolla-like. Stamens 6; anthers introrse.

115. Dioscoreaceae (p. 517). Climbing, with net-veined leaves. Flowers dioecious, small, 6-androus; perianth calyx-like. Ovules 1 or 2 in each cell.

[*][*] Ovary superior (very rarely partially adnate to the calyx in Liliaceae).

[+] 1. At least the inner perianth corolla-like; ovary compound; seeds with copious albumen.

116. Liliaceae (p. 517). Flowers perfect, 6-androus, the regular perianth corolla-like (dioecious in Smilax, dimerous in Maianthemum, the outer divisions herbaceous in Trillium). Fruit a 3-celled capsule or berry.

117. Pontederiaceae (p. 535). Aquatic, with more or less irregular perfect flowers from a spathe; perianth corolla-like. Stamens 3 or 6, mostly unequal or dissimilar. Capsule 1-celled or imperfectly 3-celled.

118. Xyridaceae (p. 536). Rush-like, scapose. Flowers capitate, perfect, 3-androus, the calyx glumaceous. Capsule 1-celled.

119. Mayaceae (p. 537). Moss-like aquatic. Flowers perfect, axillary, solitary, 3-androus; calyx herbaceous. Capsule 1-celled.

120. Commelinaceae (p. 538). Flowers perfect, regular or somewhat irregular, with 3 more or less herbaceous persistent sepals and 3 fugacious petals. Stamens 6 or some sterile. Capsule 2--3-celled.

127. Eriocauleae (p. 566). Scapose aquatic or marsh plants, with linear leaves and dense heads of monoecious (rarely dioecious) minute flowers. Corolla tubular or none. Capsule 2--3-celled, 2--3-seeded.

[+] 2. Perianth small, of 6 equal persistent glumaceous segments; flowers perfect; ovary compound.

121. Juncaceae (p. 539). Rush-like. Stamens 3 or 6. Capsule 1- or 3-celled, 3-valved.

[+] 3. Flowers without chaffy glumes, the perianth none or reduced to bristles or sepal-like scales; flowers often monoecious or dioecious; carpels solitary or united.

[++] Flowers capitate or upon a spike or spadix, with or without a spathe.

122. Typhaceae (p. 547). Marsh or aquatic plants, with linear leaves, and monoecious flowers without proper perianth, in heads or a naked spike.

123. Araceae (p. 548). Flowers perfect or monoecious upon the same spadix, rarely dioecious, with 4 or 6 scale-like sepals or none.

[++][++] Flowers very minute, one or few from the margin of a floating disk-like frond.

124. Lemnaceae (p. 551). Plants very small, green, mostly lenticular or globose.

[+] 4. Perianth of 4 or 6 segments, the inner often petaloid, or none; carpels solitary or distinct (coherent in Triglochin); seeds without albumen; aquatic or marsh plants, often monoecious or dioecious.

125. Alismaceae (p. 553). Perianth of 6 segments, the inner petal-like.

126. Naiadaceae (p. 557). Perianth-segments herbaceous or none.

[+] 5. Flowers in the axils of chaffy scales or glumes arranged in spikes or spikelets, without evident perianth; stamens 1--3; ovary 1-celled, 1-seeded; seed albuminous.

128. Cyperaceae (p. 567). Scales single. Perianth none or replaced by bristles. Anthers basifixed. Fruit a triangular or lenticular achene. Stem solid, often triangular, with closed sheaths.

129. Gramineae (p. 623). Glumes in pairs. Perianth replaced by minute scales. Anthers versatile. Fruit a caryopsis. Culm usually hollow, terete; sheaths split to the base.