MONOCOTYLEDONES 209 



Properties and Uses. — Unimportant. 



Order 28. Aroidace^e, the Armn Order.— Character. — 

 Herbs or shrubs, with commonly an acrid juice, and subter- 

 ranean tubers, conns, or rhizomes. Leaves sheathing, usuaUy 

 net-veined, simple or rarely compomid. Floiuers unisexual and 

 monoecious, or hermaphrodite, arranged on a spadix within a 

 spathe, or the spathe is absent. Perianth none, or composed of 

 scales which are inferior. Male fioiver : — Stamens few or 

 numerous ; ajithers extrorse, sessile or upon very short filaments. 

 Female jioiver : — Ovary 1- or more-celled, superior. Fruit 

 succulent. Seeds pulpy, with abmidant mealy, horny, or fleshy 

 albumen, or rarely exalbuminous ; enihryo various. 



Diagnosis. — Flowers on a spadix, and with or without a true 

 spathe. Flowers naked, unisexual and monoecious ; or herma- 

 phrodite, and then frequently with a scaly mferior perianth. 

 Anthers extrorse. Fruit succulent. 



Division of the Order and Illustrative Genera. — The order 

 may be divided into two sub-orders as follows : — 

 Sub-order 1. Aroidece or AracecE. — Flowers unisexual, monoe- 

 cious. Spadix surrounded by a spathe. Perianth none. 

 Illustrative Genera : — Arum, Li7in. ; Caladium, Vent. 

 Sub-order 2. AcorecE or Orontiece. — Flowers hermaphrodite. 

 Spadix surrounded by a spathe or naked. Perianth absent, 

 or more generally present, and then scaly. Illustrative 

 Genera :- — Acorus, Linn. ; Orontium, Linn, 

 Distribution and Numbers. — They abound in tropical 

 countries, but also occur in cold and temperate regions. There 

 are about 250 species. 



Properties and Uses. — The plants of this order are all more 

 or less acrid, and often highly poisonous. But this acrid prin- 

 ciple is frequently volatile, or decomposed by heat ; hence it 

 may be in some cases more or less destroyed by drying or ex- 

 posing to heat the parts in which it is found. The best method 

 of getting rid of the acridity is, however, by boiling in water, 

 as the acrid matter is also commonly soluble in that fluid. 

 Starch is usually associated with the acrid principle, and when 

 extracted, may be used for food like other starches. The under- 

 ground steins or conns of many species, when cooked, are eaten 

 in different parts of the world. Some are aromatic stimulants ; 

 others expectorant, antispasmodic, or diaphoretic. 



Order 2*^. LEMNACEiE,the Duckweed Order. — Character. — 

 Floating aquatic plants, with lenticular or lobed leaves or 

 fronds. Flowers 2 or 3, enclosed in a spathe {fig. 974), 



VOL. II. p 



