LINN^AN CLASS XVIII., XIX. 187 



CLASS XVIIL— GYNANDRIA. 

 Orders I. and II.— MONANDRIA and DIANDRIA 



The §renera of these orders form the Natural Order Orchidacece, No. 

 122. 



Order V.— PENTANDRIA 



Asclepias. Sepals small, 5-parted. Corolla 5-parted, reflexed. Sta- 

 minal crown 5-leaved, each with a subulated, averte process. Pollen 

 in 10 masses, arranged in pairs. Follicles 2. Seeds comose. Asclepi- 

 adacece, 79. 



Gonolobus. Calyx small. Corolla rotate, 5-parted. Starainal crown 

 shield-form, lobed. Pollen masses iu 5 pairs. Follicles 2. Asclepiada- 

 cece, 79. 



Apocynum. Calyx persistent, 6-cleft. Corolla 5-lobed, regular. 

 Estivation twisted. Stamens 5. Anthers sagittate. Follicles long, 

 linear. Apocynacece, 80. 



Amsonia. Calyx 5-parted. Corolla funnel-shaped, with the throat 

 closed. Follicles 2, erect. Seed terete. Apocynacece, 80. 



Echites. Calyx o-parted, with acute segments. Corolla funnel- 

 shaped. Throat naked. Anthers adhering to the stigma. Follicles 2, 

 long, slender. Apocynacece, 80. 



Orders VI. and X.— HEXANDRIA and DECANDRIA 

 These genera form the Natural Order Aristolochia, No. 106. 



CLASS XIX.— MONCECIA. 

 Order I.— MONANDRIA. 



Zostera. Perianth none. Stamens and j)istils separated in two rows 

 upon one side of the spadix. Drupe 1-seeded. Naiadacece, 1.39. 



Caulbia. Nojas. Perianth none. Anther 1, sessile. Style filiforn 

 Stigma 2 cleft. Capsule 1-seeded. Naiadaccie, 139. 



Euphorbia. Involucre campanulatc, 5 — 10-toothed, the inner seg 

 ments erect. Stamens attached to the inside of the involucre. Fila 

 ments articulated. Pistil central. Fruit stiped, 3-angIed, S-celled. 

 EuphorbiacecB, 108. 



Order II. 



Podostemum, Flowers naked, bursting through an irregularly lacer 

 ated spathe. Stamens monadelphous. Ovary 2-celled, capsular. 

 Seeds numerous. Podostemacect, 112. 



Lemna. Spirodela. Sterile and fei-tile flowers collateral. Perianth. 

 1-leaved. Stigma funnel-form. Capsule 1-celled, 1 — 5-seeded. Ara- 

 cecB, 138. 



Order III.— TRIANDRIA 



Typha. Flowers collected into a long, dense, cylindric spike. Sta- 

 minate florets above. Pistillate florets below, on the same axis. Fruit 

 Vei-y suiall, oblong, stipitate. Aracecv, 138. 



Spargannm. Flowers in dense, si)herical heads, the sterile ones 

 above. Perianth 3-leaved. Fruit drv, 1-secded. Aracece, 138. 



