[++] 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.