NOTABLE PLANT FAMILIES 



this characteristic is added a square stem, opposite leaves, a two- 

 lipped corolla, four stamens in pairs — two being longer than the 

 others — or two stamens only, and a pistil whose style (two- 

 lobed at the apex) rises from a deeply four-lobed ovary which 

 splits apart in fruit into four little seed-like nutlets, we may feel 

 sure that one of the many Mints is before us. 



Sometimes we think we have encountered one of the family 

 because we find the opposite leaves, two-lipped corolla, four 

 stamens, and an ovary that splits into four nutlets in fruit ; but 

 unless the ovary was also deeply four-lobed in the flower, the 

 plant is probably a Vervain, a tribe which greatly resembles the 

 Mints. The Figworts, too, might be confused with the Mints 

 did we not always keep in mind the four-lobed ovary. 



In this family we find the common catnip and pennyroyal, 

 the pretty ground ivy, and the handsome Oswego tea (p. 264). 



Mustard Family. — The Mustard family is one which is 

 abundantly represented in waste places everywhere by the little 

 shepherd's purse or pickpocket, and along the roadsides by the 

 yellow mustard, and wild radish. (See Crinkle-root, PI. V.) 



Its members may be recognized by their alternate leaves, 

 their biting, harmless juice, and by their white, yellow, or pur- 

 plish flowers, the structure of which at once betrays the family to 

 which they belong. 



The calyx of these flowers is divided into four sepals. The 

 four petals are placed opposite each other in pairs, their spread- 

 ing blades forming a cross which gives the Order its Latin name 

 Cruciferce. There are usually six stamens, two of which are in- 

 serted lower down than the others. The single pistil becomes 

 in fruit a pod. Many of the Mustards are difficult of identifica- 

 tion without a careful examination of their pods and seeds. 



Orchis Family. — To the minds of many the term orchid only 

 suggests a tropical air-plant, which is rendered conspicuous either 

 by its beauty or by its unusual and noticeable structure. 



This impression is, perhaps, partly due to the rude print i-n 

 some old text-book which endeared itself to our childish minds 

 by those startling and extravagant illustrations which are re- 



xxxvii 



