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

98. Euphorbiaceae (p. 451). Flowers moncious or dicious (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 moncious, dicious, or (in Ulmeae) perfect. Seeds exalb.u.minous or nearly so. Inflorescence very various.

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

100. Platanaceae (p. 466). Trees, with alternate palmately lobed leaves, sheathing stipules, and moncious flowers in separate globose heads.

Ovary superior; fruit a club-shaped nutlet.

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

102. Myricaceae (p. 469). Shrubs, with resinous-dotted leaves, with or without stipules, and moncious or dicious 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 moncious. 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). Dicious 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 dicious, scaly-bracted. Sepals somewhat petaloid or none. Embryo axile in copious alb.u.men.

[+] 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 moncious, minute, axillary and sessile. Alb.u.men none; the seed filled with a highly developed embryo.

SUBCLa.s.s 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 moncious or dicious flowers.

CLa.s.s 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 alb.u.men, very numerous and minute.

108. Hydrocharidaceae (p. 495). Aquatics, with dicious 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 alb.u.minous. (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 dicious, 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 alb.u.men.

116. Liliaceae (p. 517). Flowers perfect, 6-androus, the regular perianth corolla-like (dicious 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 moncious (rarely dicious) 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 moncious or dicious; 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 moncious flowers without proper perianth, in heads or a naked spike.

123. Araceae (p. 548). Flowers perfect or moncious upon the same spadix, rarely dicious, 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.