[+] 4. Perianth of 4 or 6 segments, the inner often petaloid, or none; carpels solitary or distinct (coherent in Triglochin); seeds without alb.u.men; aquatic or marsh plants, often moncious or dicious.

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 alb.u.minous.

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.

SERIES II. CRYPTOGAMOUS OR FLOWERLESS PLANTS; dest.i.tute of stamens and pistils, in fructification producing _spores_ instead of seeds.

CLa.s.s 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.

SUBCLa.s.s 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. Equisetaceae (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. Ophioglossaceae (p. 693). Fronds often fern-like, erect in vernation. Sporangia globose, coriaceous, 2-valved, in special spikes or panicles.

133. Lycopodiaceae (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. Selaginellaceae (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. Marsiliaceae (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. Salviniaceae (p. 701). The two kinds of spores in separate thin-walled 1-celled sporocarps or conceptacles cl.u.s.tered beneath the small floating fronds; macrospores solitary.

SUBCLa.s.s 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 HEPATICae, 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. Jungermanniaceae (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. Anthocerotaceae (p. 726). Thallus without epidermis, irregularly branching; pedicels stout or none. Capsule with a columella. Elaters mostly without fibres.

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

a.n.a.lYTICAL KEY TO THE ORDERS.

CLa.s.s I. DICOTYLEDONOUS PLANTS. (See p. 1.)

SUBCLa.s.s I. ANGIOSPERMae. Pistil consisting of a closed ovary.

Cotyledons only two.

DIVISION I. POLYPETALOUS: the calyx and corolla both present; the latter of _separate_ petals.

[A.] _Stamens numerous, at least more than 10, and more than twice the sepals or lobes of the calyx._

[1.] _Calyx entirely free and separate from the pistil or pistils._

PAGE Pistils numerous but cohering over each other in a solid ma.s.s on an elongated receptacle. MAGNOLIACEae, 49

Pistils numerous, separate, but concealed in a hollow receptacle.

Leaves opposite, entire; no stipules. CALYCANTHACEae, 167

Leaves alternate, with stipules. Rosa, in ROSACEae, 162

Pistils several, immersed in hollows of the upper surface of a large top-shaped receptacle. Nelumbo, in NYMPHaeACEae, 55

Pistils more than one, separate, not enclosed in the receptacle.

Stamens inserted on the calyx, distinct. ROSACEae, 150

Stamens united with the base of the petals, monadelphous.

MALVACEae, 96

Stamens inserted on the receptacle.

Filaments much shorter than the anther; trees. ANONACEae, 50

Filaments longer than the anther.