2. Leaves pinnately compound or dissected, forming a crown at the top of the stem. Stem simple or scantily branched towards the top. Juice mucilaginous. Perianth none. Stamens with numerous pollen-sacs. Embryo with 2 more or less connate cotyledons. [Class CYCADALES.] =1. Cycadaceae.= Leaves undivided, scattered along the branches of the stem, rarely (_Gnetaceae_) leaves 2, arising from the top of an undivided turnip-shaped stem and sometimes splitting lengthwise. Stamens with 1-9 pollen-sacs. Embryo with 2-15 free cotyledons 3 3. Perianth present. Juice not resinous. Leaves not needle-shaped. Shrubs. [Class GNETALES.] =4. Gnetaceae.= Perianth absent. Juice resinous, rarely scarcely so, but then leaves needle-shaped. Leaves needle-or scale-shaped. [Class CONIFERAE.] 4 4. Seeds overtopping the fleshy or rudimentary carpels and surrounded by a fleshy aril. Carpels with 1 ovule =2. Taxaceae.= Seeds concealed between the carpels, without an aril. Carpels usually with 2 or more ovules =3. Pinaceae.= 5. (1.) Embryo with a single cotyledon, rarely undivided. Vascular bundles scattered in the stem. Leaves usually parallel-veined (net-veined in many _Araceae Dioscoreaceae_ and _Taccaceae_ and a few _Hydrocharitaceae Liliaceae_ and _Orchidaceae_), generally narrow entire and sessile with a dilated base. Flowers usually 3-merous. [Class MONOCOTYLEDONEAE.] 6 Embryo with 2 cotyledons, rarely with only one well-developed cotyledon or undivided. Vascular bundles of the stem nearly always disposed in a cylinder. Leaves usually net-veined, rarely sessile with a dilated base and a narrow entire blade. Flowers usually 4-or 5-merous. [Class DICOTYLEDONEAE.] 52 6. Perianth wanting or rudimentary, that is, reduced to small, hypogynous, free or partially-united scales, rarely (_Potamogetonaceae_) replaced by sepaloid appendages of the connective. 7 Perianth well developed, calyx-or corolla-like or consisting of calyx and corolla, rarely (_Eriocaulaceae_ and _Restionaceae_) wanting in the female flowers. 15 7. Flowers in the axils of membranous or more or less dry bracts (glumes) in spikelets consisting of one or several flowers and one or several empty glumes and nearly always arranged in spikes, racemes, panicles, or heads. Land-, marsh-, or freshwater-plants. Carpel solitary, with a single basal or laterally attached ovule 8 Flowers in spadices with a fleshy rachis and surrounded by one or several spathes, more rarely solitary or in glomerules, heads, or spikes; in the latter case (_Potamogetonaceae_) saltwater 9 8. Embryo enclosed in the lower part of the albumen. Seed and ovule attached at the base, free from the pericarp and the wall of the ovary. Style 1, with 1-3 stigmas. Anthers usually affixed at the base. Sheaths of the cauline and inner radical leaves closed all round, usually without a ligule. Stem usually triangular solid and without nodes. =17. Cyperaceae.=