374 COLLEGE BOTANY 



The sweet potato (IpomoBa batatas) is a tropical and semi- 

 tropical plant, which is grown and used extensively for food. 

 Its origin is not definitely known; some authorities claiming 

 that it is Asiatic while others claim that it is indigenous to both 

 Asia and America. 



The dodder or love vine (Cuscuta) also belongs to this fam- 

 ily. There are many species, all of which are parasitic on other 

 plants. The seeds germinate in the soil, the stem twines about 

 other plants, the lower part dies, thus leaving it attached tO' its 

 host. Some species are destructive to agricultural plants, espe- 

 cially the clovers. 



LABiATiE (Mint Family). — Mostly herbs with square stems ; 

 flowers axillary, in cymose clusters or spikes or racemes ; perfect, 

 irregular ; fruit developed into four achene-like lobes or nutlets ; 

 leaves simple, opposite or whorled and aromatic. This 

 family contains a great many interesting plants. A few will 

 be mentioned. 



Mentha piperita is the well-known peppermint and Mentha 

 viridis the spearmint. One or both of these plants were culti- 

 vated in Europe as early as the ninth century. They are used 

 for flavoring and to some extent in medicines. M. puegium is 

 the pennyroyal which has been introdiiced from the old world. 

 It also possesses some medicinal properties. 



This family also contains sweet thyme (Thymiis vidgaris 

 and T. serpyllum), which is used for seasoning and in 

 medicines; the well-knovrai garden sage (Salvia officinalis), 

 which was introduced from the old world and is used for 

 flavoring in foods; catnip or catmint (Nepeta cataria) and 

 hoarhound (Marrubium vidgare), which have certain medic- 

 inal properties. 



SoLANACBiE' (Nightshade Family). — Herbs, rarely shrubs; 

 leaves alternate; inflorescence solitary, fascicled or corym.bose, 

 axillar)' or terminal; flowers perfect, usually regular; sepals 



