538 
DIADELPHIA. 
Class XVII. 
Class XVII. — DIADELPHIA. Stamens united in two separate parcels. 
This class essentially, requires, as its name implies, that the stamens should be united in two separate parcels. 
These may either be equal, each bearing more anthers than one, as in Smithia, iEschynomene, Fumaria, and 
others ; or unequal, one parcel being reduced to a single stamen, and the other bearing several anthers, as in 
the greater number of genera included in the class. But besides the plants whose stamens are thus disposed, 
it has been the practice to admit other genera having papilionaceous flowers, but with their stamens united in 
one parcel only, such as Platylobium, Bossiaea, Arachis, and others. I he propriety of this measure is extremely 
questionable. It has been before remarked in this work, that the value of an artificial arrangement of objects 
depends wholly upon the precision with which they are referred to those heads or divisions with the characters 
of which they agree. If this doe.s not obtain, an artificial system ceases to be useful, and its only merit, that 
of facilitating the discovery of the name of a given object, cannot be said to exist. This principle is particularly 
applicable to the genera just mentioned. Their artificial character refers them to Monadelphia, but they 
are retained in Diadelphia, to which tlieir artificial character does not refer them, because, as is alleged, of the 
natural relation which they bear to other genera in Diadelphia. If this reasoning, which is only applicable to 
an arrangement of plants according to their natural affinities, and which has no allowable reference to an arti- 
ficial system, were to be admitted, it would follow that Tamariudus, actually included in Monadelphia by the 
most eminent Linnean botanists, and all th-e papilionaceous genera stationed in Decandria, should be referred 
hither also. With such objections attaching to the contrivance of this class, it is not easy to understand in 
what way it " does honor to the comprehensive powers of Linnaeus's mind," as has been somewhere remarked 
by one of his most distinguished panegyrists. 
The structure of the corolla of plants of this class is, for the most part, with the exception of Fumaria and 
its allies, what has been popularly termed papilionaceous ; that is to say, it consists of five petals of different 
forms and direction, of whicli the vjjper, called the vexillum or standard, is larger than the rest, upon which it 
is incumbent ; the two lateral, called the alee or wings, are oblong, distinct, and parallel with the ovarium ; and 
the two lower, called the carina or keel, are enclosed within the alae, are also parallel with the ovarium, and 
cohere by their lower edges, so as together to form, as it were, one boat-shaped petal. To this common form 
of corolla there are, however, some exceptions, as in Amorpha, where the ate and carina are absent, and in 
Erythrina, where the alcE are in some cases almost obliterated. In Trifolium the petals all cohere by their claws 
into an undivided tube. 
With regard to the importance of Diadelphous plants as applicable to the purposes of mankind, they may be 
said to hold the very highest rank. All the numerous varieties of pulse, whether eaten by men or cattle, peas, 
beans, haricots, caravances, lentils, and others, are all produced by Diadelphous plants. The best of our arti- 
ficial grasses, such as clover, nonesuch, cow-grass, lucerne, saintfoin, serradilla, &c. &c., belong to various Dia- 
delphous genera. A large proportion of the class also consists of useful and ornamental trees and herbs, whicli 
will be noticed in their respective places. 
Order 1. PENTANDRIA. Stamens 5. 
1500. Momnieria. Cal. 5-parted, with the upper segment long. Cor. ringent. Stamens 2 : upper with two 
anthers ; lower with three. Caps. .'5, 1-seeded. 
1501. Petalostemum. Petals 4, between the stamens, all united into a slit tube. Vexillum none, but in its 
place a fifth petal. Legume surrounded by calyx, 1-seeded. 
Orders. HEXANDRIA. Stamens 6. 
1502. Corydalis. Pet. 4, 1-spurred at base. Pod 2-valved, compressed, many-seeded, 
1503. Cysticapnos. Petals 4, one gibbous at base. Capsule bladdery, many-seeded j the placentas connected 
by a membranous net work. 
1504. Diclytra. Petals 4, two outer equally spurred or gibbous at base. Pod 2-valved, many-seeded. 
1505. Adlumia. Petals 4, united in a fungous monopetalous corolla, persistent, and with two protuberances 
at base. Pod 2-ralved, many-seeded. 
1506. Sarcocapnos. Petals 4, 1-spurred at base. Caps. 2-valved, not opening, 2-seeded. Valves 3-nerved, 
flattish. 
1507. Fumaria. One petal gibbous or spurred at base. Cariopsis indehiscent, 1-seeded, not pointed with a 
style. 
Orders. OCTANDRIA. ^^^^ Stamens 8. 
1508. Polygala. Cal. of 5 leaves, two of them wing-shaped and colored. Caps, compressed, obcordate. 
1509. Muraltia. Sepals 5, glumaceous, nearly equal. Petals 3, united, the middle bifid with blunt lobes. 
Ovary with 4 horns or tubercles, 2-valved, 2-celled. 
1510. Mundia. Sepals 5, glumaceous, persistent, the two inner wing-shaped. Petals 3, scarcely united at 
base ; the middle one cucullate, beardless. Stamens 7-8, somewhat villous, monadelphous at base, with a tube 
divided in front. 
1511. Securidaca. Sepals 5, the two inner petaloid. Petals 5, united at base : three united into a 3-lobed 
keel ; two oblong. Stamens 8, diadelphous. 
Order 4. DECANDRIA. Stamens 10. 
1512. NissoUa. Cal. 5-toothed. Legume 1-seeded, ending in a ligulate wing. 
1513 Dalbergia. Cal. obsoletely 5-toothed. Legume leafy, flat, not opening. Seeds solitary or twin. 
1514. Pongamia. Cal. colored, cyathiform, obliquely truncate, S-toothed. Petals clawed, Vexillum spread- 
ing. Ala; and carina conniving. Legume substipitate, compressed, flat, rostrate, valveless, l-2.seeded. Anthers 
ciliate, glandular at end. 
1515. Ptcrocarpus. Cal. 5-toothed. Legume falcate, foliaceous, varicose, indehiscent, encompassed by a 
wing. Seeds a few, solitary. 
1516. Ecastaphyllum. Cal. carapanulate, sub-bilabiate : upper segment emarginate j lower trifid. Filaments 
equally diadelphous. Legume roundish, valveless, 1-seeded, 
