GROUPS AND ORDERS. 25 



21. Galiaceous plants herbs ; leaves and leaf-like stipules 



forming radiate whorls around the square stem ; cells of the 

 carpels one-seeded. 



}J Carpels one-celled, one-seeded. 



22. Valerianaceous plants herbs ; stamens fewer than the 



lobes of the corolla ; anthers distinct. 



23. Composite plants herbs ; stamens equalling in number the 



divisions of the corolla (i. e. isomerous) ; anthers united into 

 a tube around the style (i. e. syngenesious). 



Stamens perigynous. 

 t Seeds attached to a free central placenta. 



24. Primulaceous plants herbs ; stamens equalling in number 



and opposite to the lobes of the corolla. 



ft Seeds attached to the sides of the carpels, or in the 

 axial angle of the cells. 



{ Corolla regular or nearly so. 



25. Apocynaceous plants herbs; corolla contorted, the stamens 



isomerous, alternating with its lobes ; ovaries two, distinct, 

 cohering by their stigma. 



26. G-entianaceous plants herbs; stamens isomerous, alter- 



nating ; ovary of 1-2 many-seeded cells ; placentas parietal. 



27. Boraginaceous plants herbs ; stamens isomerous, alter- 



nating ; ovary four-lobed, with one ovule in each lobe. 



%% Corolla irregular. 



28. Scrophulariaceous plants green leafy herbs ; ovary two- 



celled, the cells many- seeded; placentas axile. 



29. Orobanchaceous plants brown leafless herbs ; ovary two- 



celled, the cells many-seeded ; placentas parietal. 



30. Labiate plants green leafy herbs ; flowers unsymmetrical ; 



ovary four-lobed, with one ovule in each lobe. 



