A. - Butomus umbellatus, Linnaeus: p. 125.

1. A flower with the perianth removed.

2. One of the carpels.

3. A transverse section of the carpels. B. - Typha latifolia, Linnaeus: p. 121.

1. A male flower, separate.

2. A female flower, separate.

C. - Acorus Calamus, Linnaeus: p. 123.

1. A flower with its green scales and stamens, and broad sessile stigma.

2. One of the scales with its accompanying stamen, separate.

3. An ovary.

D. - Potamogeton natans, Linnaeus: p. 123.

1. One of the flowers.

2. A stamen, separate.

3. One of the carpels.

E. - Lemna trisulca, Linnaeus: p. 122.

1. A frond with its branches and root.

2. A flower.

F. - Juncus efiusus, Linnaeus: p. 124.

1. A portion of the cylindrical stem.

2. A flower.

3. A capsule with the dry persistent perianth. G. - Carex riparia, Curtis: p. 129.

1. A flower of the male spikelet with its glume.

2. A flower of the female spikelet with its glume.

Plate 21.

Butomus umbellatus

Butomus umbellatus

Typha latifolia

Typha latifolia

Acorus Calamus

Acorus Calamus

Poiamogeton nataris

Poiamogeton nataris

Lemna trisulcas

Lemna trisulcas

Juncus effusu

Juncus effusu

Carex riparia

Carex riparia

W Fitch. del. et. bith

Vincent Brooks Lmp