SPERMATOPHYTA— FARINOSAE 



373 



from trees, and by the pine-apple {Ananas sativus), a well known fruit now 

 cultivated extensively in Florida; from which has been isolated the enzyme, 

 bromelin, a powerful ferment capable of rapidly digesting vegetable and animal 

 albumen. It acts in the presence of either acid or alkaline carbonates and is 

 related to trypsin and pepsin. In the same family is the pinguin {Bromelia 

 Pinguin) or wild pine-apple, the slightly acrid pulp of which is edible and the 

 fiber valuable. The plant is armed with stout spines which made the passage 

 of troops difficult in the late Spanish war. 



In the same order are the Spiderworts belonging to the family Commelin- 

 aceae. The common blue spiderwort {Tradescantia virginiana) of sandy and 



Fig. 161. Common Rush {Junciis 

 tenuis). A weed with tough stems, 

 along beaten paths and roadsides. (Char- 

 lotte M. King.) 



