LIBER. 



[ 462 ] 



LICHENOPOEA, 



bo readily seen in the long woody radicles 

 developed from the seeds of the Rliizopho- 

 rese (PI. 48. fig. 31) ; and in the bark and 

 pericarp of Gnetum, isolated branched 

 liber-libres occur scattered throughout the 

 whole mass. 



In many Dicotyledons the thick-walled 

 liber-cells are formed only in the first year, 

 the subsequent formation in this region 

 consisting of new layers of vasa propria 

 and parenchymatous cells {Betula alba 

 and Fagus sylvatica). In Viburnu^n Lan- 

 tana the thick-walled liber is entirely 

 wanting. 



In the Monocotyledons they occur asso- 

 ciated with short wood-cells in the fibro- 

 Tascular bundles ; but they form alone the 

 fibrous bundles often intermixed with and 

 prolonged from the ends of these, occui-ring 

 especially in the outer part of the stem of 

 herbaceous Monocotyledons, such as Lihes 

 and Grasses, and in the fleshy cortical layer 

 of rhizomes, as in Sparganiwn, kc. 



In both families they occur with the spiral 

 vessels and wood-cells in the ribs or veins 

 of leaves (as in Phormium tenax), bracts, 

 spathes of Palms, &c. 



Liber-cells are generally drawn out very 

 gradually to a point at each end ; sometimes 

 they are very long ; Schleiden states he has 

 seen them 5" or 6". Sometimes they exhi- 

 bit expansions at particular points, as in 

 the Apocynaceae. The branched forms 

 in Rhizophorea?, Gnetum, &c. are usually 

 much shorter than the simple fibres, and 

 their form is often very irregular (PI. 48. 

 fig. 31). The diameter varies a great deal 

 in some plants ; and we should scarcely ven- 

 ture to say that the microscopic appearance 

 of a liber-fibre would suffice for the deter- 

 mii^ation of the material of any (vegetable) 

 textile fabric, beyond the distinction of 

 cotton (or vegetable hair) from linen or other 

 liber ; but reagents affect them differently. 

 The appearance presented by many kinds 

 of fibre under the microscope, in the state 

 in which they occur in commerce and after 

 treatment with acids, is shown in PI. 28. 

 figs. 2-7, 25 & 20. The figures are taken 

 from very characteristic exiim])l('S : but mnny 

 modifications occur in subordinate qiiaiitity. 

 Flax (Linnm tisitatissimvm) (fig. 2) has the 

 walls much thickened, with distinct pores ; 

 it exhibits a very oblique close striation after 

 boihug with nitric acid. Jute, the liber of 

 Corchorus capsnlaris, has thinner walls, with 

 constrictions at intervals and blunter ends 

 (fig. 3) ; no spiral streaks come out here on 



boiling with nitric acid. The fibre from the 

 Cocoa-nut husk occurs in bundles (fig. 4) ; 

 when isolated or boiled with acid, the walls 

 are found thin, with wide, open, spiral streaks 

 (slits in the secondary layers) ; the ends are 

 blunt (fig. 5 a, b). The fibre of hemp {Can- 

 nabis saliva) somewhat resembles flax, but 

 is coarser and becomes swollen up and brit- 

 tle, readily breaking across, when boiled with 

 nitric acid (fig. 6) ; no spiral streaks. The 

 liber-fibres from the bundles of Miisa textilis 

 (fig. 7) are fine and tough, and not much 

 altered by boiling. Those of Bcehmeria 

 nivea (fig. 25) are coarse, rough on the out- 

 side ; they swell up and exhibit marked spiral 

 slits when boiled ^Yith acid, and also distinct 

 lamination of the thick wall (fig. 25 c). Boeh- 

 meria Piiya (fig. 26) closely resembles the 

 former ; but the spiral striation is not very 

 evident, and the wall sphts readil_y in the 

 longitudinal direction (fig. 20 c). The spiral 

 striation is well seen in fig. 30 of PI. 48, 

 which represents the end of a liber-fibre from 

 Tinea minor after boihng with nitric acid. 



The liber-bimdles of bark are sometimes 

 set free as loose stringy fibres by the decay 

 of the outer parts of the bark, as in the vine. 

 Clematis, &c. In some plants they take a 

 wavy course, anastomosing laterally so as to 

 form connected reticulated sheets over the 

 cambium : in the Lime {Tilia) these sheets 

 may be detached by maceration, and they 

 form bast, the material used for matting, 

 &c. In the Thymeleace.^ (lace-bark 

 trees) the annual layers of liber can be 

 detached from each other, and form sheets 

 of fibrous tissue, sometimes firm and tough, 

 sometimes almost as delicate as muslin. 



BiBL. Mohl, Bot. Zeit. xiii. 873 ; Schacht, 

 Pflanzenzelle, 208; Ann. Sc. Nat. 4 s(5r. viii. 

 104 ; Hachs, Bot. 121 ; Henf rey-Masters, i?oi!. 



See also under Laticifeeous Tissue. 



LICEA, Schrad. — A genus of Myxomy-' 

 cetes, growing on damp rotten wood, in 

 garden frames, &c., with the peridia elon- 

 gate, grouped together, of only one layer, 

 and containing few or no filaments among 

 the spores. Four species are described as 

 British, of which L. fragifonnis, Nees, is 

 not uncommon on wet very rotten wood, 

 moss, &c.; the groups of peridia just before 

 maturity somewhat resembling a straw- 

 berrv, afterwards brownish. 



BiBL. Berk. Br. Fl. ii. pt. 2. 321 ; Ann. 

 N. H. 2 ser. v. 307 ; Greville, Sc. Crypt. Fl. 

 pi. 328 : Fries, Syst. Mycol. iii. 195 ; Sum. 

 Veg. 458. 



LICHENOP'ORA, Def.— A genus of 



