SPERMATOPHYTA 405 



Metachlamydeae, in which the floral formula is typically 5-5-10-5. They 

 are more primitive than the other sympetalous orders and more closely 

 related to the Archichlamydeae. They are, with few exceptions, regular 

 and hypogynous. 



The following orders comprise tlie tetracyclic anisocarpic series of 

 Metachlamydeae, in which the floral formula is generally 5-5-5-2. Here 

 belong three hypogynous and two epigynous orders. 



Gentianales. This is a genetic order. It comprises about 5,000 spe- 

 cies of herbs and woody plants separated into 5 families, the principal 

 ones being the Oleaceae, Gentianaceae, and Asclepiadaceae. The Olea- 

 ceae is represented by the olive (Olea), ashes (Fraxinus), lilacs (Syringa), 

 and privets (Ligustrum); the Gentianaceae by the gentians {Gentiana); 

 and the Asclepiadaceae by the milkweeds (Asclepias). The flowers are 

 regular, tetramerous or pentamerous, tetracyclic, anisocarpic, hypogy- 

 nous, and apocarpous or syncarpous. They have two carpels. The 

 Oleaceae have the peculiar floral formula of 4-4-2-2. 



Tubiflorales. This great central order of Metachlamydeae is closely 

 related to the Gentianales and difficult to separate from it. It includes 

 20 families and about 16,000 species, most of which are herbs. The eight 

 principal families, with several representative genera, are as follows : Con- 

 volvulaceae — bindweed (Convolvulus), morning-glory (Ipomoea), and 

 dodder (Cuscuta); Polemoniaceae^ — Polemonium, Phlox, and Gilia; Hydro- 

 phyllaceae — Hydrophyllum, Nemophila, and Phacelia; Boraginaceae — 

 forget-me-not (M yosotis) , bluebells (Mertensia), and Heliotr opium; Verbe- 

 naceae — Verbena and Lantana; Labiatae — sage (Salvia) and mint (Men- 

 tha); Solanaceae — nightshade (Solarium), tobacco (Nicotiana), and 

 Petunia; Scrophulariaceae — mullein (Verbascum), foxglove (Digitalis), 

 and snapdragon (Antirrhinum). 



The flowers of the Tubiflorales are regular or irregular, mostly pentam- 

 erous, tetracyclic, anisocarpic, hypogynous, and syncarpous. They have 

 two carpels (three in Polemoniaceae). The corolla is mostly regular in all 

 families except the Verbenaceae, Labiatae, and Scrophulariaceae, where it 

 is almost always irregular. These three families have only four stamens, 

 or sometimes only two, while the others have five. The ovary is uniloc- 

 ular or bilocular in the Hydrophyllaceae ; mostly bilocular in the Convol- 

 vulaceae, Solanaceae, and Scrophulariaceae ; mostly trilocular in the Pol- 

 emoniaceae; and mostly tetralocular in the Boraginaceae, Verbenaceae, 

 and Labiatae. 



Plantaginales. These are the plantains, comprising one family of 

 about 200 species of herbs. The principal genus is Plantago. The 

 flowers are regular, tetramerous, tetracyclic, anisocarpic, hypogynous, 

 and syncarpous. They have two carpels. The corolla is dry and mem- 

 branaceous. This order is related to the Tubiflorales. 



