Vessels 



( 427 ) 



Viburnum 



two classes, viz. true vessels and ground tissue 

 vessels. The true vessels may be subdivided into 

 (1) those of the wood (xylein) and (2) those of 

 the bast (phloem). They are associated in the 

 tibro- vascular tissue of the stems and leaves both 

 of Monocotyledons and Dicotyledons. 



First taking the vessels of the wood, it will 

 be found that they can be conveniently classified. 

 according to the thickening of the walls, into 

 spiral, annular, reticulated, and scalariform. The 

 spiral and annular vessels have a spiral thickening, 

 which may be likened to a spiral coil of wire 

 enclosed in a glass tube. In the annular vessels 

 the coils of the spiral are very close. The reticu- 

 lated vessels have the thickening disposed in net- 

 work fashion, while the scalarifnrm ones show the 

 thickenings on their walls to be arranged to re- 

 semble the rungs of a ladder. At first filled with 

 protoplasm, the vessels of the wood soon lose this, 

 and in their later stages are only filled with air, or 

 air and sap at certain times of the year. The wood 

 cells or wood fibres seen in company with these 

 vessels are long, very narrow tubes, with lignified 

 walls and tapering and overlapping ends ; their 

 function is to impart strength and rigidity. Some- 

 times their walls are pitted like those of the vessels, 

 but their transverse walls are not absorbed ; in 

 this state they are known as tracheides, as apart 

 from the true trachese or vessels. 



The vessels of the bast (phloem) appear as thin 

 and very slender ducts with thin and not at all 

 rigid walls, the transverse partitions being only 

 partly absorbed. These partly absorbed walls are, 

 however, perforated in various places, the per- 

 forated partitions being known as "sieve plates," 

 and the vessels themselves as "sieve tubes." These 

 vessels of the bast are filled with protoplasmic or 

 mucilaginous contents. Bast fibres resemble the 

 wood fibres in shape and disposition, but they have 

 not lignified walls, and their functions are to give 

 toughness and elasticity rather than rigidity. 



The vessels of the ground tissue are chiefly 

 represented by the lactiferous receptacles to be 

 found in plants belonging to such natural orders as 

 Papaveraceas, Euphorbiacese, and Asclepiadeae. 

 They may originate, not by the union of cells, but 

 by the growth and branching of a single cell. It 

 has been suggested that they may even be inter- 

 cellular spaces into which the latex has been 

 forced. In a work of this scope it is impossible to 

 go into detail, and the reader is recommended to 

 some of the excellent works upon morphological 

 botany which exist. 



The vascular or fibro-vascular system of plants 

 is composed of bundles made up of the vessels 

 referred to in combination with their accompanying 

 tracheides and companion cells and, in the Dico- 

 tyledons, the all-important layer of cambium which 

 lies between the xylem and phloem. That is as 

 far as the stem is concerned. In the root the 

 xylem and phloem are dissociated and alternate 

 with each other, instead of the one lying behind 

 the other. The cambium is here represented by 

 the pericambium which encloses the central axis 

 formed by these strands of xylein and phloem. 



Again referring to the stem, a different arrange- 

 ment of the bundles prevails in Monocotyledons 

 from that seen in Dicotyledons. In the latter the 

 bundles are " open " or " indefinite," and possessing, 

 as they do, a cambium layer, growth is only limited 

 by the life of the tree. In the fibro-vascular 

 bundles of Monocotyledons there is no cambium 

 layer, the bundles are said to be " closed " or 



"definite," and little increase in size of the stem 

 takes place. 



In all flowering plants the bundles pass from the 

 stem into the leaves, and hence are known as 

 "common" bundles. In the higher Cryptogams 

 there are " cauline " bundles, which only branch 

 into the leaves. 



All plants possessing avascular system are styled 

 vascular plants. 



VESTIA. (CHILIAN BOX-THORN). 



An interesting greenhouse shrub (on/. Solanacese), 

 propagated by cuttings of half-ripe shoots under a 

 glass in sand, and thriving in loam and peat with 

 a little sand. 



Only Species : 



lycinides, I!', .Te., yel. 



VIBURNUM. (GUELDER ROSE.) 

 A large genus (tird. Caprifoliaceze) of deciduous, 

 or evergreen shrubs or trees, principally hardy, of 

 easy cultivation, and many very ornamental in 

 the shrubbery or garden. Propagation, by layers 

 or by cuttings of half-ripe shoots in sandy soil, 

 under hand-lights. Common soil. Viburnums are" 

 prized for forcing to flower in winter and early 

 spring. Take from the open ground in October. 

 pot, and plunge them in the open or in a cold 

 frame until wanted to be brought into heat from 

 December onwards. For this purpose the greater 

 number are valuable Tinus, the common Lauristi- 

 nus, beiag very suitable. Opulus is one of the 

 most ornamental of our native shrubs, with its 

 large flower heads followed by bunches of pinkish 

 berries. Opulus sterile is one of the most popular 

 and effective shrubs, with its large, globular heads 

 of white flowers in profusion. Lantana, the Way- 

 faring Tree, is a good hedge plant. 

 Principal Species and Varieties : 



cassinoides, 6", Je., yel., 

 wh. (xtfiis. nucluiu cas- 

 sinoides and squama- 

 tum). 



dentatum, 5' to 10', Je., 

 bl. or pur. American 

 Arrow Wood. 



variegatum, Ivs. varie- 

 gated. 



dilatatum, 10', Je., wh. 



inacrocephalum, 20', Je., 

 wh. (*//. Fortunri of 

 gardens). 



ocloratissimum, G' to 10', 

 My., wh., ev., fragrant. 



Opulus, & to 8', Je., wh. 

 (//*. edule and Oxy- 

 coccus). Guelder Rose, 

 Suowball Tree, Cran- 

 berry Tree, etc. 

 - foliis-variegatis, Ivs. 

 wh., yel. 



nauum, about 1' high. 



sterile, all the flowers 

 sterile, the best. (Jar- 

 den Guelder Rose or 

 Snowball Tree. 



prunifolium, 6' to 12', 

 My., wh. (SI/H. piri- 



folium). American 



Black Haw. 



Tinus, 8' to 10', Dec. to 

 Mch., ev., wh., ro. 

 Laurustinus. 



Frrebeli, whiter, Ivs. 

 lighter. 



hirtum, blooms in aut. 

 and win., Ivs. hairy 

 below. 



- lucidurn, larger than 

 type. There is also a 

 variegated form. 



purpureum, Ivs. pur- 

 plish. 



rotundifolium, Ivs. 

 round. 



strictum, rather up- 

 right in habit. 



strictum variegatum, 

 Ivs. variegated. 



variegatum, Ivs. varie- 

 gated wh. 



tomentosum, 4' to 6', My., 

 wh. (//. plicatum of 

 Siebold and Zuccarini). 



plicatum, 4' to 6', My., 

 wh., sterile flowers. 



I it '// (.svr I i/'fii . 



Velch, Jiastard or Jikjdder (see Phaca). 



]'ffi'/i, ISilli'r l.\vr Orobus). 



Vflfli, Chicliliny fwr faithi/rut tativut). 



Vrteh, Croren (see Cortmilla). 



Vetrli, Liifiwrii-r (Attrayalu* i/Iyi-ipfiyllut). 



Vetch, Mrdiclt (see Oniibryehis). 



Vetch, Milk (see Astrayalus). 



