NATUEAL ORDERS. Ixxiii 



LXVI. Spurge family. Flowers unisexual. Fruit separating into 3 (rarely 

 2 or more) carpels, leaving a persistent axis, each carpel containing one or two 

 pendulous seeds. 



LXVII. Empetrum genus or family. Differs from the Spurge family in 

 the ovules and seed erect. 



LXVIII. Ceratophyll and Callitriche. Anomalous aquatic genera. Peri- 

 anth none. Ovary with 1 or 4 cells, and one seed in each. 



LXIX. Nettle family. Flowers unisexual, small and green. Stamens op- 

 posite the perianth-divisions (usually 4). Ovary free, with a single ovule, and 

 2 (rarely 1) styles or stigmas. 



LXX. Elm tribe or family. Trees. Flowers often bisexual, the stamens 

 opposite the lobes. Ovary free, 2-celled, with one erect ovule in each cell. 



LXXI. Catkin family. Trees or shrubs. Flowers unisexual, the males in 

 catkins with an imperfect perianth, or none at all. Fruit of the females one- 

 celled. 



LXXII. Pine family or class. Trees or shrubs with stiff or scale-like leaves. 

 Flowers unisexual, the males in catkins without perianth. Ovules and seeds 



the females not enclosed in any ovary or pericarp. 



CLASS II.— MONOCOTYLEDONS. 



In germination the plumule is developed from a sheath-like cavity on one 

 side of the embryo. 



# Perianth none, or of 4 small sepals or bracts. 



LXXIII. Bulrush family. Flowers unisexual, intermixed with bracts in 

 dense heads or spikes. Fruit a dry nut. 



LXXIV. Arum family. Flowers unisexual, often intermixed with bracts, in 

 dense heads or spikes, mostly in a spatha. Fruit usually succulent. 



LXXY. Duckweed genus. No distinct stem. Flowers (very scarce) on the 

 edge of the small leaf-like floating fronds. 



LXXVI. Naias family. Floating or submerged plants. Flowers distinct, 

 or in loose spikes. Stamens 1, 2, or 4. Ovaries 1, 2, or 4. 



** Perianth tvholly or partially petal -like. Ovary apocarpous. 

 LXXYII. Alisma family, the only known British one. 



### Perianth wholly or partially petal-like. Ovary inferior. 



LXXYIIL Hydrocharis family. Floating or submerged plants. Flowers 

 usually unisexual. Perianth regular, with a slender tube. 



LXXIX. Orchid family. Perianth very irregular. Anther 2-celled, com- 

 bined with the style in an axile column. 



LXXX. Iris family. Like the Amaryllis family, but stamens 3. Leaves 

 often in two opposite rows. 



LXXXI. Amaryllis family. Terrestrial plants. Perianth of 6 divisions. 

 Stamens 6. 



LXXXI I. Yam family. Twining plants. Flowers unisexual. Perianth 

 regular, of 6 divisions. 



### Perianth regular. Ovary syncarpous, superior. 



LXXXIII. Lily family. Perianth petal-like. 



LXXXI Y. Rush family. Perianth stiff, or calyx- like. Capsule 3-celled, 

 with several seeds, or one erect seed in each cell. 



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