FAMILIES OF FLOWERING PLANTS 



143 



tate or palmately lobed or divided; the flowers, mostly large and showy, 

 are quite irregular in structure, the calyx being prolonged into a nectar- 

 bearing spur. The 5 petals are borne usually on long claws; stamens 

 5; ovary usually 3-celled, capsular in fruit (see Fig. 125, no. 1). It is 

 Tropaeolum mqjus which is such a universal favorite in our gardens, 

 and which commonly bears the name " Nasturtium." This is an inex- 

 cusable misnomer, for Nasturfiu7n was known for years as the genus- 

 name of the water-cress; and the fact that the latter is now known by 

 another scientific name {Eorippa) does not excuse the misappellation 

 of Nasturtium. The word Tropaeolum is easy to pronounce and to 

 remember. 



Family Linaceae. Flax 

 Family. Includes 4 genera and 

 about 150 species of wide geo- 

 graphic distribution in both 

 temperate and tropical regions. 

 The family is remarkable for 

 the regularity and symmetry of 

 its flowers, which have 4 or 5 

 sepals, 4 or 5 alternating petals, 

 4 or 5 stamens, and a 2-5-celled 

 ovary (see Fig. 125 no. 2). 



The genus Linum is a large 

 one, containing numerous North 

 American, south European and 

 African species. While several 

 are in garden cultivation, the 

 only one of importance is the 

 common flax {L. usitatissimum). 

 This has been in cultivation 

 since the earliest times, and is 

 one of those plants that is not 

 now known to occur in the wild state. Besides the use of the fiber from 

 its stems in the manufacture of fine linen, the seeds, when soaked in 

 water, yield a mucilaginous substance possessing medicinal properties, 

 and when pulverized an oil known as linseed oil is expressed from them, 

 the resulting oil-cakes being extensively used for fattening cattle. 



Family Humiriaceae. Humiria Family. A group of South Amer- 

 ican trees comprised in 3 genera and about 20 species. Humiria hal- 

 samifera yields a reddish balsamic juice, which when dry is burned as 

 an incense. A medicinal ointment is also prepared from it. The struc- 

 ture of the flowers in this family is similar to that of the Linaceae, but 

 the fruit is a drupe instead of a capsule. 



Fig. 125. Cross-sections of flowers; i, Tropaeo- 

 lum pentaphylluni. 2. Flax {Linum usitatissimu»i)\ 

 3a and 3b. Redwood {Erythroxylon pulchrum) show- 

 ing two forms of stamens and pistils. All natural 

 size. Redrawn from Engler. 



