140 SUMMER FLOWERS. 



with as many alternating stamens ; ovary four-celled, with a 

 single ovule in each cell affixed at the base of the cavity. 



X+ Corollas irregular. 

 § Ovary four-lohed. 



49. Labiate plants — herbs ; corolla two-lipped ; stamens usually 



four didynamous (2 long, 2 short), or sometimes only two ; 

 lobes of the ovary one-seeded. 



§§ Ovary undivided {i.e. not lohed). 



50. Verbenaceous plants — herbs ; stamens four didynamous, 



rarely two ; ovary four-celled, dividing when mature into 

 four one-seeded nuts. 



51. Scrophulariaceous plants — herbs ; stamens four, didyna- 



mous ; ovary two-celled, the cells many- seeded ; placentas 

 axile. 



52. Orobanchaceous plants — leafless parasitical herbs ; stamens 



four, didynamous ; ovary one-celled, with two or more many- 

 seeded parietal placentas. 



Monoclllainyds : Perianth single {i. e. consisting of a calyx 

 only) , or altogether wanting^ and replaced by scaly bracts ; 

 Orders 53 to 59. 



* Carpels solitary, simple. 

 t Calyx inferior. 



53. Chenopodiaceous plants — herbs ; leaves without stipules ; 



perianth small, the stamens (4-5, rarely 1-2), alternating 

 with its lobes ; cvule 1-celled, with one ovule. 



54. Ceratophyllaceous plants — aquatic floating herbs ; leaves 



without stipules ; perianth none ; ovary and fruit 1- seeded, 

 or 4-lobed, with one seed in each lobe. 



55. XJrticaceous plants — herbs ; leaves with distinct stipules ; 



flowers unisexual ; perianth small, green, the stamens, 

 usually 4, opposite its segments ; styles two, rarely one. 



