ORDER MONOGYNIA. 213 



ments of a plant. The St. John's wort, Hypericum, a very 

 common and numerous genus, is in the family Lysimachi. 



In this comprehensive order of the class Pentandria, we find 

 the morning glory (Convolvulus), and the genus Ribes, which 

 contains the currant and gooseberry. The coffee (Coffea Ara- 

 bica) is also in this class and order. This plant is a native of 

 Arabia ; it is said to be used to a great extent by the Turks 

 and Arabs, to counteract the narcotic effects of opium, which 

 they use in large quantities. It is remarked by a physician, 

 that the question is often asked, which is the least detrimental 

 to health, tea or coffee ; he says, the Turks, who drink great 

 quantities of coffee, and the Chinese, who make equally as free 

 use of tea, do not exhibit such peculiar effects as render it easy 

 to decide, whether they are, in reality, deleterious to the hu- 

 man system. 



The trumpet-honeysuckle (honicera), belongs to this part of 

 the artificial system (Fig. 108, b) ; it has a very minute, five- 

 cleft calyx, which is superior or above the germ ; the corolla is 

 of one petal, and tubular ; the tube is oblong ; the limb of the 

 corolla is deeply divided into five revolute segments, one of which 

 seems separated from the others ; the filaments are exserted ; 

 the anthers are oblong. 



Before closing our remarks upon this order, we will remind 

 you that the wine grape is found here. The general character 

 of the grape (Vitis), is a calyx five toothed ; petals connected 

 at the top ; a five seeded, round pericarp. The stamens and 

 pistils are, in some genera, dio3cious, or on separate plants ; this, 

 according to our principles of classification, would carry the 

 genus into the class Dio3cia ; but as some species of the genus 

 have perfect flowers, containing five stamens and one pistil, and 

 as it is never permitted to separate the different species of a 

 genus, we take the dioecious species, which are less numerous 

 than the pentandrous, into the fifth class. 



The regions which produce the wine grape have a mean 

 annual temperature* of 50 degrees on the northern border, and 

 59 degrees on the southern. Lines of temperature have been 

 described by Humboldt, by remarking the peculiar vegetables 

 in different countries. He has traced the northern limit of the 

 wine grape, where the mean annual temperature is about 50 



* By mean annual temperature, is meant a medium between the extremes of 

 heat and cold. In a climate where the thermometer in summer would rise to 

 100 degrees, and in winter sink to zero or 0, the medium would be 50 degrees ; 

 this is probably not far from the mean annual temperature of our climate. The 

 mean annual temperature at the equator is reckoned to be about 84 degrees. 



Coffee Trumpet-honeysuckle Vitis Temperature of the regions which 

 produce the wine grape What do you understand by mean annual tempera- 

 ture l(See Note.) 



