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

107. Coniferæ (p. 489). Resiniferous trees or shrubs, with mostly awl-shaped or needle-shaped and evergreen leaves, and monœcious or diœcious 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.

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

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

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

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

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

112. Hemodoraceæ (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. Iridaceæ (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. Amaryllidaceæ (p. 515). Often bulbous-rooted and scapose. Perianth corolla-like. Stamens 6; anthers introrse.

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

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

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

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

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

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

120. Commelinaceæ (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. Eriocauleæ (p. 566). Scapose aquatic or marsh plants, with linear leaves and dense heads of monœcious (rarely diœcious) 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. Juncaceæ (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 monœcious or diœcious; carpels solitary or united.

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

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

123. Araceæ (p. 548). Flowers perfect or monœcious upon the same spadix, rarely diœcious, 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. Lemnaceæ (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 monœcious or diœcious.

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

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

Series II. CRYPTOGAMOUS or FLOWERLESS PLANTS; destitute of stamens and pistils, in fructification producing spores instead of seeds.

Class III. ACROGENOUS PLANTS.

Cryptogamous plants with a distinct axis (stem and branches), growing from the apex only, and furnished for the most part with distinct leaves (sometimes taking the form of an expanded leaf-like usually prostrate thallus); reproduction by means of antheridia and archegonia, sometimes also by gemmation.

Subclass I. VASCULAR ACROGENS, or PTERIDOPHYTES. Stems (and foliage when present) containing both woody fibre and vessels; antheridia or archegonia, or both, borne on a minute prothallus, which is developed from the spore on germination.

[*] Spores of only one kind; prothallus bearing antheridia and archegonia.

130. Equisetaceæ (p. 675). Cylindric jointed hollow-stemmed plants, with toothed sheaths. Fructification in a terminal spike.

131. Filices (p. 678). Ferns, with fronds circinate in vernation, bearing the fructification on the under surface or beneath the margin.

132. Ophioglossaceæ (p. 693). Fronds often fern-like, erect in vernation. Sporangia globose, coriaceous, 2-valved, in special spikes or panicles.

133. Lycopodiaceæ (p. 695). Low moss like plants with elongated stems and small persistent entire several-ranked leaves. Sporangia solitary, axillary, 1–3-celled, 2–3-valved.

[*][*] Spores of two kinds, the macrospore producing a prothallus with archegonia, the microspore smaller and developing antheridia.

134. Selaginellaceæ (p. 697). Low leafy moss-like or marsh plants, with branching stems, and small 4–6-ranked leaves, or with a corm-like stem and basal linear-subulate leaves, the two kinds of spores in distinct solitary axillary 1-celled sporangia.

135. Marsiliaceæ (p. 700). The two kinds of spores in the same or different sporangia which are borne in a coriaceous peduncled sporocarp arising from a slender creeping rhizome. Fronds digitately 4-foliolate or filiform.

136. Salviniaceæ (p. 701). The two kinds of spores in separate thin-walled 1-celled sporocarps or conceptacles clustered beneath the small floating fronds; macrospores solitary.

Subclass II. CELLULAR ACROGENS, or BRYOPHYTES.

Plants with cellular tissue only; both antheridia and archegonia borne upon the plant itself.—Including the Musci, or Mosses (which are not treated of here), never thallose, and bearing capsules which usually dehisce by a lid and contain spores only, and the Hepaticæ, which bear capsules which dehisce by valves or irregularly and usually have elaters mingled with the spores. The latter division comprises the following Orders.

[*] Capsule 4-valved; plant a leafy axis or sometimes a branching thallus.

137. Jungermanniaceæ (p. 702). Leaves, when present, without a midrib, 2-ranked, with often a third row beneath; pedicels slender.

[*][*] Capsule 2-valved, or dehiscing irregularly, or indehiscent; plant a thallus or thalloid stem.

138. Anthocerotaceæ (p. 726). Thallus without epidermis, irregularly branching; pedicels stout or none. Capsule with a columella. Elaters mostly without fibres.

139. Marchantiaceæ (p. 727). Thallus radiate or dichotomous, the epidermis usually porose. Capsules borne on the under side of a pedunculate receptacle, irregularly dehiscent. Elaters 2-spiral.

140. Ricciaceæ (p. 730). Thallus radiate or dichotomous, the epidermis eporose. Capsules immersed in the thallus or sessile upon it, indehiscent. Elaters none.