SYSTEMS OF BOTANICAL CLASSIFICATION. 



177 



frlaments; as in tlie mallow and marsh-mal- 

 low. 



Class XVII. Diadelphia. — Stamina varying 

 in numljer, united by their filaments into two 

 distinct bodies. Of this kind are the fumitory, 

 the milkwort, and most of the Icguminosa;, as 

 the acacia, laburnum, liquorice, melilot. 



ClassXVIII.Polyadei.phia. — Staminaunited 

 liy their filaments into three or more bundles. 

 As in the genera Hypericum, Cisttis, Melaleuca. 



6. Union of the Stamina by the anthers. 

 Class. XIX. Syngexesia. — Five stamina 

 united by the anthers: flowers generally com- 

 pound, rarely simple. This class contains the 

 flosculossE, semiflosculostE, and radiata: of Tour- 

 nefort. It also contains certain other plants, 

 such as the genera Lobelia, Viola. 



C. Union of the Pistil and Stamina. 

 Class XX. Gynandria. — Stamina united into 

 one body with the pistil. To this class belong 

 all the orchidese, the genus Aristolochia. 



7. Flowers unisexual. 



Class XXI. Mon(ecia. — Male flowers and 

 female flowers distinct, but both occuiring on 

 the same individual. As in the oak, the box, 

 the maize, the arrow-head, the castor-oil plant. 



Class XXII. Dicecia. — Male flowers and 

 female flowers existing on two separate indi- 

 viduals of the same species, as in mercurialis, 

 the date-palm, the misseltoe, willows, the pistacia. 



Class. XXIII. Polyoamia. — Hermaphrodite 

 flowers, male flowers and female flowers occun-- 

 ing together on the same individual, or on dif- 

 ferent plants, as in the ash, the pellitory, the 

 crosswort. 



8. Flowers invisible. 



Class XXIV. Cryptogamia. — Plants whose 

 flowers are invisible, or very indistinct. This 

 class contains the ferns, such as the polypody, 

 osmunda; mosses, lichens, equiseta, algce, fungi. 



We have now given a brief account of the 

 characters of each of the twenty-four classes 

 established by Linnaeus in the vegetable king- 

 dom. It will be seen that the an-angement of 

 this system is simple, and easily understood. 

 Indeed, one might at first think that ho had 

 nothing more to do than to count the number 

 of stamina in a flower, to know the class to 

 which it belongs; but, in many cases, this de- 

 termination is not so easy as might at first be 

 supposed, and one is very often left in doubt, 

 especially when the plant presents some unusual 

 anomaly. 



The Orders. In the first thirteen classes, 

 the characters of which are taken from the 

 number of the stamina, those of the orders have 

 been obtained from the number of styles or dis- 



tinct stigmas. Thus a plant belonging to the 

 class Pentandria, such as the parsnip or any 

 other umbelliferous plant, which may have two 

 styles or two distinct stigmas, is referred to the 

 second order. Should it have three, it will be- 

 long to the third order, &c. These orders are 

 designated as follows : — 



Order 1. Monogynia, one style. 



Order 2. Digynia , two styles. 



Order 3. Trigynia, three styles. 



Order 4. Tetragynia, four styles. 



Order 5. Pentagynia, five styles. 



Order 6. Hexagynia, six styles. 



Order 7. Ilcptagynia, seven styles. 



Order 8. Decagynia, ten styles. 



Order 9. Polygynia, numerous styles, 

 I,t is to be remarked, that there are classes in 

 which this entire series of orders does not occur. 

 In Monandria, for example, there are only two 

 orders : Monogynia, to which belongs the genus 

 Hippuris; and Digynia, which contains the 

 genus Blitum. 



In Tetrandria, there are three orders : Mono- 

 gynia, Digynia, and Tetragynia. There are six 

 in Pentandria, and in the classes following a 

 variable number. 



In the fourteenth class, Didynamia, Linnseus 

 has founded the characters of the two orders 

 into wliich he divides it, upon the structure of 

 the ovary. The fruit is sometimes formed of 

 four small akenia, situated at the bottom of the 

 calyx, and which he considered as four naked 

 seeds. Sometimes, on the other h,and, it is a 

 capsule, which contains a variable number of 

 seeds. The first order bears the name of Gym- 

 nospermia (naked seeds,) and contains all the 

 true labiatoe, such as the genera Marrubium, 

 PMomis, Nepeta, Scutelaria. The second order, 

 which is named Angiospermia (enclosed seeds,) 

 and of which a capsular fruit is chai-acteristic, 

 contains all the Personatae of Toumefort, such 

 as the genera Rhinanthiis, Linaria, Melampyrum, 

 Orobanche. 



Tetradynamia, the fifteenth class, has also two 

 orders, derived from the foi-m of the fi-uit, which 

 is a siliqua or a silicula. Accordingly, wo have 

 first tetradynamia siliculosa, containing the plants 

 of which the fruit is a silicula, such as the genera 

 /satis, Cochlearia, Thlaspi, &c.; and secondly, 

 tetradynamia siliquosa, containing those of which 

 the fi-uit is a siliqua; as the wall-flower, cabbage, 

 the water-cress. 



The sixteenth, seventeenth, and eighteenth 

 classes Monadelphia, Diadelphia, and Polyadel- 

 phia, have been established on the union of the 

 staminal filaments into one, two, or more distinct 

 bundles, without regard to the number of stamina 

 of which these bundles consist. Linnaius has, 

 in this case, employed the characters derived 

 from the number of the stamina to form the 

 I orders of these three classes. Thus the plants 



