478 BOTANY. 



count ; but in a general view they protect other plants from 

 the severity of cold, and form an important part of the process 

 by which sterile or naked rocks are gradually covered by vegeta- 

 tion. Among the ferns are found substances useful in medi- 

 cine and the arts. 



It is in the family of Grasses (Graminete), however, that the 

 most useful plants are found. It is sufficient to mention wheat, 

 rye, barley, oats, rice, and maize, which form the chief food of 

 men and cattle. One species is well known as affording in 

 abundance the sugar of commerce. The stalks of the Cypera- 

 ceos and TypJiacece, which vegetate in marshes and ponds, are 

 employed to cover houses, in the manufacture of mats, &c. and 

 one of the family furnished the ancients with their papyrus, or 

 paper for writing. 



The family of Aroidece are singular for the faculty which 

 the plants possess of entrapping flies. By their disagreeable and 

 cadaverous shell, the flies are attracted to deposit their ova, 

 and are retained by the particular structure of some spines. 

 The palms of eastern countries are particularly valuable to the 

 natives of these countries. The stems, the sap, the fruit, are 

 all turned to useful purposes, and even the twigs are formed in- 

 to mats, seats, and cordage. The date palm is well known as 

 furnishing a grateful food ; another species affords by distilla- 

 tion the spirituous liquor known by the name of arrack. The 

 Asparaginece produce some useful medicines, as sarsaparilla, 

 dragons-blood, &c. and the young shoots of one species are es- 

 teemed for the table. The Juncece, from the flexibility of their 

 stems, are employed for many purposes ; and some species, as 

 ordinary saffron (Crocus sativus), and the meadow saffron 

 (Colchicum autumnale), are used in medicine. 



Among the Liliacece, the bulbs of the Scilla and others are 

 employed in medicine ; and many are- cultivated as ornamen- 

 tal in gardens. Several very useful plants occur in this family, 

 as the onion, the shalot, and the anana. From the bulbous roots 

 of some Orchidece are drawn Salep ; the Scitaminea? furnish a 

 grateful food in the banana to the inhabitants of the torrid zone. 

 The LauristinecB afford cinnamon and sassfrass ; the Jasminece 

 the olive ; and the Labiatce camphor and aromatic oils. 



The family of Solanece, by a singular contrast, contains some 

 of the strongest vegetable poisons and one of the most useful 



