377 



LEGUMINOS^E. 



LEGUMINOS.E. 



373 



indefinite, perigynous, rarely hypogynous, either distincj, or mona- 

 delphous, or diadelphous, very rarely triadelphous ; anthers versatile ; 

 pistil simple, superior, 1-celled, 1- or many-seeded, commonly con- 

 sisting of a single carpel, but occasionally of 2 or even of 5 carpels ; 

 style simple, proceeding from the upper margin ; stigma simple ; 

 fruit either a legume or a drupe ; seeds attached to the upper suture, 

 solitary or several, occasionally with an aril ; embryo with or without 

 albumen, either straight, or with the radicle bent upon the cotyledons ; 

 cotyledons either remaining underground in germination or elevated 

 above the ground, and becoming green like leaves, always very large 

 in proportion to the radicle, and very often amygdaloid. 



The most common feature of Leguminous Plants is to have what 

 are called papilionaceous flowers, and when these exist no difficulty is 

 experienced in recognising them, for papilionaceous flowers are found 

 nowhere else. Another character is to have a leguminous fruit : and 

 by one of these two characters all the plants of the order are known. 

 It is remarkable however that one or other of these distinctions dis- 

 appears in a great many cases. Ctual-piniea have an irregular flower 

 with spreading petals and stamens adhering to the calyx ; others have 

 no petals at all, or some number less than five, while Mimoeeie have 

 perfectly regular flowers and indefinite hypogynous stamens. Detarium, 

 I>ipteryjc, and others, instead of a legume have a fruit not distinguish- 

 able from a drupe. This last circumstance is easily to be understood 

 if we bear in mind that a legume and a drupe differ more in name 

 than reality, the latter being formed on precisely the same plan as the 

 former, but with this modification, that its pericarp is thickened, 

 more or less fleshy on the outside and stony ou the inside, 1-seeded, 

 and indehiscent. Hence some of the regular flowered genera with 

 distinct stamens may be said to be rosaceous iu flower and leguminous 

 in fruit. Simple therefore as the diagnosis of this order usually is, 

 Brown is perfectly correct in asserting that, until he indicated the 

 difference of the position of the odd lobe of the calyx in Leguminous 

 Planta and Roseworta, no positive character had been discovered to 

 distinguish the one order from the other. Very few double flowers 

 are known in this order ; those of Spartium junceum and Ulex Ewopam 

 are the most remarkable. Two ovaries are common in \\'itlaria 

 Sineiuit, and the same phenomenon is to be seen, according to De 

 Candolle, in I ilcilitchia. On account of these and other circum- 

 stances, De Candolle assumes the carpel of Leguminous Plants to be 

 solitary by abortion, and that a whorl of 5 is that which is necessary 

 to complete the symmetry of the flowers. 



In consequence of the highly irritable nature of the leaves of many 

 of the plants of this order, and of the tendency to irritability discover- 

 able in them all, some botanists have placed them at the extremity of 

 their system, in contact with the limits of the animal kingdom. For 

 observations upon the nature of this irritability see Dutrochet, ' Sur 

 la Motilitc,' Paris 1824, in which the author endeavours to show that 

 the motion is the effect of galvanic agency ; and the same writer's 

 'Nouvelles Rechercheg sur I'Exosniose,' in which he alters the 

 explanation of the manner in which galvanism produces the motion, 

 adhering however to his opinion of that subtle principle being the 

 real agent. It is more probable however that these movements are 

 connected with the inherent irritability of the protein common to all 

 plants. 



In many respects this order is one of the most important which the 

 botanist can study ; more especially as it serves to show how little 

 real importance ought to be attached to dehiscence of fruit in deter- 

 mining the limits of natural orders. What may be called the normal 

 fruit of Leguminous Plants is a legume, that is to say, a dry simple 

 carpel, with a suture running along both its margins, so that at 

 maturity it separates through the line of each suture into two valves ; 

 but every conceivable degree of deviation from this type occurs. 

 Arachi* and many more are indebiscent ; in Carmichalia the valves 

 separate from the suture, which remains entire, like the replum of 

 Crucifera ; in all Lomentaceous genera, such as Ornithopus, the valves 

 are indehiscent in the line of the suture, but separate transversely ; 

 in Entada a combination of the peculiarities of C'armichcelia and 

 Lomentacea occurs ; in Jlcematozylon the valves adhere by the suture 

 and split along the axis ; and finally, Detariun, Dijiteryx, and others, 

 are true drupes, in no respect different from those of Aiayydalere. 



The geographical distribution of this order has been considered with 

 great care by De Candolle, from whom the substance of what follows 

 is borrowed. One of the first things that strikes the observer is, that 

 if a number of genera of Leguminous Plants have as extensive a 

 range as those of other orders there is a considerable number of which 

 the geographical limits are clearly defined. Thus, the genera of 

 Australia are in most cases unknown beyond that vast island ; the 

 same may be said of north and South America, and the Cape of Good 

 Hope ; and there are 14 or 15 genera unknown beyond the limits of 

 Europe and the neighbouring borders of Asia and Africa. About 92 

 genera out of 280 are what are called ' sporadic,' or dispersed over 

 different and widely-separated regions, such as Tephronia, Acacia, 

 Glycine, and Sophora, The species are found more or less in every 

 part of the known world, with the exception of the islands of Tristan 

 d'Acugna and St. Helena, neither of which do they inhabit; but 

 they ara distributed in extremely unequal proportions. In general 

 they diminish sensibly in approaching the pole. This will be apparent 

 from the following table : 



Europe, with the exception of the Meditemn >au . 184 



Siberia 129 



United States 183 



Cdina, Japan, and Cochin China .... 77 



Levant 250 



Basin of the Mediterranean . - . . . . 468 



Canaries 21 



Arabia and Egypt 87 



Mexico 152 



West Indies . 221 



East Indies . 452 



Equinoctial America 605 



Equinoctial Africa 130 



Australia . 229 



Isles of Southern Africa 42 



South America beyond the tropics ... 29 



Cape of Good Hope 353 



South Sea Islands 13 



This distribution, if condensed, will give the following results : 



Equinoctial Zone 1602 



Beyond the Tropics to. the North . . . . 1312 



Beyond the Tropics to the South .... 524 



Since the time this calculation was made the order has been pro- 

 digiously enlarged and a very considerable number of species has 

 been added to those from the tropical parts of America, Australia, 

 and the Cape of Good Hope. Nevertheless the calculation, with these 

 exceptions, is instructive as a general sketch of the statistics of this 

 branch of Geographical Botany. The Leguminous order is not only 

 among the most extensive that are known, but also one of the most 

 important to man, whether we consider the beauty of the numerous 

 species, which are among the gayest-coloured and most graceful plants 

 of every region, or their applicability to a thousand useful purposes. 

 The properties of the order are very various : some are nutritious, 

 others tonic and astringent, others purgative, and some poisonous. 

 The plants supply timber, fibres, gum, dyes, and various other econo- 

 mical articles. There is however to be borne in mind, in regarding 

 the qualities of this order in a general point of view, that upon the 

 whole it must be considered poisonous, and that those species which 

 are used for food by man and animals are exceptions to the general 

 rule. 



The species amount to some thousands, and are conveniently divided 

 into three sub-orders, Papilionaeeee, Ciesalpiniece, and Mimosea. 



Papilionaeeee, Pulse section, have what are called papilionaceous 

 flowers, that is, of the five petals one is large, broad, spread open, and 

 called the standard; two others are parallel, convex, or slightly 

 spreading, and called wings ; and the two remaining ones are also 

 parallel, but united by their anterior edge so as to form a body not 

 unlike the keel of a boat, after which it is named. In all these plants 

 the stamens are definite in number, and inserted with tolerable 

 distinctness into the calyx ; but while many are diadelphous, others 

 are monadelphous or decandrous; the fruit is either a legume, a 

 lomentum, or a drupe, or some form intermediate between the first 

 and last. It is here that the great mass of the orderoccurs, especially 

 in the colder parts of the world. Peas, beans, clover, saiutfoin, 

 lucern, liquorice, indigo, medick?, and trefoils, lupiues, and numerous 

 other common European genera, belong to Papilionaeeee. 



Iniiigofcra Anil. 



1, Standard ; 2, wings ; 3, keel of the flower ; 4, calyx ; 5, 

 sta:: cn ; 6, legume. 



diadclphous 



