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€3)e Crea^ttru at 38ntang. 



676 



longingto the natural order Laminariacece, \ 

 with a tall thick stem, branched above and ' 

 bearing at each tip a pair of lanceolate | 

 leaves which hang down for a foot or more 

 in length. The species form large sub- 

 marine forests, and the stems when thrown 

 ashore look like wood ; hence they are some- 

 times collected by seamen for firewood, to 

 their great disappointment when they at- 

 tempt to use them. They are employed 

 more profitably for knife handles, and other 

 similar purposes. The blade is fixed in 

 when the plant is moist, and is effectually 

 fastened by its contraction when dry. The 

 stems have a kind of false exogenous 

 growth, of which a representation may be 

 seen in Berkeley's Introduction to Crypto- 

 gamic Botany, p. 56. The new rings seem 

 to depend upon the growth of the leaves, 

 whereas in the large Laminariece where 

 a similar structure occurs, it depends 

 upon the development of new roots or 

 holdfasts. Lessonice are principally at home 

 in the southern hemisphere. [M. J. B.] 



LETHARGIA. A name applied in vege- 

 table pathology to those cases in which the 

 buds of transplanted plants and grafts, or 

 the embryos of seeds, though still possessed 

 of vitality, are sluggish and either are not de- 

 veloped at all, or are expanded imperfectly. 

 Close pruning is often necessary to over- 

 come this evil in plants which are not re- 

 moved till spring; and artificial means, as 

 the application of hot water, weak solutions 

 of acids, &c, are sometimes needful to over- 

 come the suspended animation of seeds. 

 Some roots, again, like those of orchids, oc- 

 casionally lie dormant in the soil for years, 

 where they are excluded from the light by 

 an overgrowth of shrubs. Ophrys muscifcra 

 and some other species in certain districts 

 appear only after the underwood has been 

 cut down. Portions of the tubers of dahlias, 

 again, if no part of the crown be left, will 

 live for years without throwing out a single 

 bud. [M. J. B.] 



LETTERED. Marked with letter-like 



6pOtS. 



LETTER-LEAP or LETTER-PLANT. 

 Grammatophyllum. 



LETTER-WOOD. Brosimum AuMetii, 

 sometimes called Piralinera guianensis. 



LETTSOMIA. A name given by Ruiz 

 and Pavon to a genus of Ternstromiacece, 

 since united with Freziera ; and by Rox- 

 burgh to a convolvulaceous genus which 

 has proved to be identical with Argyreia. 



LETTUCE. Lactnca. -.BLUE. Mul- 

 gedium. — , CABBAGE. Those varieties 

 of garden lettuce which form low de- i 

 pressed cabbage-like hearts. — , COS. The j 

 erect-growing crisp-leaved varieties of gar- I 

 den lettuce. — , FALSE. Mulgedium. — , 

 GARDEN. Lactuca sativa. — , LAMB'S, j 

 Yalerianella olitoria. — , PRICKLY. Lac- 

 tuca Scariola. — , SEA. (Fitcus vesiculosus.) 

 — , WILD. Lactuca virosa. 



LEUCADENDRON. A genus of rrotea- | 

 ceous plants, mostly shrubs or small trees, i 

 natives of the Cape of Good Hope and the I 



south-eastern parts of Africa, distinguished 

 by having the calyx either four-cleft or with 

 four sepals, each of which bears a nearly 

 sessile anther, and a filiform style with an 

 oblique club-shaped stigma. The seed-vessel 

 is one-celled, containing a single wingless 

 seed. The involucre is generally imbri- 

 cated ; the dioecious flowers (white or yel- 

 low) are produced in small heads ; and the 

 leaves are generally sessile, simple, entire, 

 occasionally covered with white silky hairs. 

 L. argenteum, the Witteboom or Silver tree 

 of the Cape colonists, was formerly of great 

 importance for firewood, but it is now near- 

 ly extirpated. [R. jj.] 



LEUC^ENA. A genus of Leguminosce, of 

 the suborder Mimosece, characterised by 

 having the ten stamens of a Mimosa, with 

 the fiat two-valved pod of an Acacia. It 

 consists of half a dozen trees or shrubs, all 

 natives of central or South America, or the 

 Pacific Islands, with twice-pinnate leaves, 

 and small white flowers in globular heads. 

 One species, L. glanca, is much cultivated as 

 an ornamental tree in most warm climates, 

 and has become naturalised and apparently 

 wild in several parts of Africa and Asia. 

 In Europe it will bear the winter only in 

 the warmer parts of the Mediterranean re- 

 gion, where it is occasionally planted. 



LEUCANTHEMUM. A name given to the 

 Ox-eye Daisy, Chrysanthemum Leucanthe- 

 mum, and a few other species, which have 

 been distinguished from other Chrysanthe- 

 mums as a genus on account of some very 

 slight differences in the achenes. 



LEUCAS. A genus of Labiata?, having 

 the upper lip of the corolla concave, usually 

 entire and hairy on the outside, the lower 

 lip spreading, its middle lobe largest ; hav- 

 ing also the end of the style of two unequal 

 pieces, the upper of which is shortest. 

 They are herbs or shrubs, natives chiefly 

 of tropical Asia and Africa. The flowers 

 are white, rarely purple. [G. D.J 



LEITCERIA. A genus of Compositcp of 

 the suborder Mvtisiacece, consisting of eight 

 or nine Chilian herbs, with erect or ascend- 

 ing stems, more or less clothed with white 

 cottony wool. The leaves are mostly pin- 

 nately divided, cottony underneath, the 

 flower-heads small in terminal panicles. The 

 involucre is hemispherical and imbricate, 

 the outer florets radiating; the pappus con- 

 sists of shortly plumose bristles. None of 

 the species offer any particular interest 

 either as useful or ornamental plants. 



LEUCHTENBERGIA. A remarkable ge- 

 nus of Cactaceos,_ of which the only species, L. 

 principis, a native of Southern Mexico, has 

 been introduced to European gardens. In 

 this plant the mammillae, as the variously- 

 shaped projections seen in most Cacti are 

 called, grow very long, and being of a suc- 

 culent nature and three-sided shape, they 

 somewhat resemble aloe leaves, but bear 

 tufts of long chaffy or horny scales on their 

 apex. The plant itself grows a foot or 

 more high, the lower part of the stem being 

 about as thick as a man's arm, hard and 



