790 



LORANTHACEiE. 



[Epigynous Exogens. 



of that genus to consist of 4 anthers grown to the inner face of 4 calycine sepals. The 

 rim exterior to the calyx, which has given rise to the idea that the coloured part of a 

 Loranth is corolla, is present in Viscum also, in the form of a slight annular swelling ; 

 and is in all probability analogous to the raised line terminating the cup, from the rim of 

 which the sepals spring in Chryseis or Eschscholtzia. In fact, we must in theory regard 

 the flower of a Loranth to consist of a fleshy cup-like expansion of the end of a branch, 

 from the upper edge of which expansion the sepals rise. This point being settled, we 

 then have no difficulty in admitting the near alliance of Loranths and Sandalworts ; a 

 fact not lost sight of by Dr. Brown in his Prodromus ; he also, in speaking of his Myzo- 

 dendrese, or feathered Loranths, again adverts to the resemblance between their three 

 ovules suspended from the apex of a central placenta, and the same part in Sandalworts. — 

 Linn. Trans, xix. 232. Decaisne too, recognises their apetalous condition, and refers them 

 to the neighbourhood of Sandalworts. They may also be looked upon as having consider- 

 able analogy with Proteads, which must be considered to occupy a place in the peri- 

 gynous sub-class parallel with that of Loranths in the epigynous. The occasional sepa- 

 ration of the $ and $ in different flowers points strongly to a relation to some diclinous 

 Order, which relation seems to be found in Helwingiads. See p. 296. 



In some respects this singular Order offers very curious deviations from the ordinary 

 structure of similar plants. The wood of Viscum is described by Decaisne as consisting, 

 when young, of eight woody bundles surrounding a green pith ; in these bundles are 

 no spiral vessels, but instead, and nearly in the place where they are usually found, 

 some ringed tubes ; these, together with elongated and dotted or reticulated cells and 

 fibres analogous to those of the fiber, make up all the longitudinal tissue of the plant. 

 On the outside of these bundles of woody matter, and opposite to them, are found others, 

 similar in number but smaller, and composed exclusively of fibres of the liber. — Memoire 

 sur le Developpement du Gui. Brown states that hi Myzodendron the whole woody tissue 

 consists of ladder-shaped vessels (v. scalariformia), a structure very different from that 

 of other genera of Loranths. 



In the genus Viscum the anther forms its pollen in a number of distinct cavities, in 

 1 the same way as in iEgieeras ; this has been 



beautifully illustrated by Decaisne, (Acad. Roy. 

 Brux. XIII. t. 1.) 



The production of the ovules and their fertilisa- 

 tion is attended with some of the most curious 

 phenomena known in the vegetable kingdom, not 

 the least of which is that in Viscum the ovule 

 does not appear till three months after the pollen 

 has exercised its influence ; and another, that the 

 young ovules sometimes become consolidated, the 

 result of which is the presence of two or more 

 diverging embryos in the same seed. See M. 

 Decaisne's Memoir above quoted, 

 and also that of Griffith, On the De- 

 velopment of the Ovules of Loranthus 

 and Viscum, in the Linnean Trans- 

 actions, vol. xviii. p. 71, for many 

 other important particulars. 



The nature of the parasitism of these 

 plants is very curious, and has been 

 most carefully described by Griffith. 

 He states that in Loranthus the ripe 

 seeds adhere firmly to the substance 

 on which they are applied, by means 

 of their viscid coating, which hardens into a transparent glue. In two or three days after 

 application, the radicle curves towards its support, and as soon as it reaches it becomes 

 enlarged and flattened. By degrees a union is formed between the woody system of 

 the parasite and stock, after which the former lies exclusively on the latter, the fibres 

 of the sucker-like root of the parasite expanding on the wood of the support " in the 

 form of a pate d'oie." Prior to that time the parasite had been nourished by its own 

 albumen, which is gradually absorbed. "As soon as the young parasite has acquired 

 the height of one or two inches, when an additional supply of nourishment is perhaps 

 required, a lateral shoot is sent out, which is, especially towards the point, of a green 



Fig. DXXIV.— Viscum album. 1. a cross section of the stem (Decaisne) ; 2. (j> flowers ; 3. <J flowers 

 (Schleidcn) ; 4. the fruit cut perpendicularly ; 5. a pair of embryos united where they come in contact 

 ( Decaisne). 



Fig. DXXIV. 



