790 



LORANTHACE^. 



[Epigynous Exogens. 



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

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

 Loi'anth is corolla, is present in Viscum also, in the fonn of a shght annular swelling ; 

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

 which the sepals spring in Ciu'yseis 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 bemg settled, we 

 then have no difficulty in admittmg the near alhance of Loranths and Sandalworts ; a 

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

 dendi'eae, 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 theu- apetalous condition, and refers them 

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

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

 gynous sub-class parallel ^vith 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 fovmd in Helwiugiads. See p. 296, 



In some respects this singular Oi'der offers very curious dcA-iations from the ordinary 

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

 when yomig, of eight woody bimdles sui'roundiug a green pith ; in these bundles are 

 no spiral vessels, but instead, and nearly m 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 hber, 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 m number but smaller, and composed exclusively of fibres of the liber, — Memoire 

 sur le Developpement du Gui. Brown states that in Myzodeudron the whole woody tissue 

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

 of other genera of Loi^anths. 



In the genus Viscum the anther foims its pollen in a number of distinct canities, in 

 , the same way as in ^Egiceras ; this has been 



beautifully illustrated by Decaisne, (Acad. Hoy. 

 Brux. XIII. t. 1.) 



The production of the o^niles and their fertilisa- 

 tion is attended with some of the most curious 

 phenomena known in the vegetable kingdom, not 

 the least of wliich is that in Viscum the o\iile 

 does not appear till three months after the pollen 

 has exercised its mfluence ; and another, that the 

 young ovules sometimes become consoUdated, 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- 

 relopment 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 m Loranthus the ripe 

 seeds adhere firmly to the substance 

 on which they are apphed, by means 

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

 application, the radicle cm'ves 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 fomier hes 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." Pi-ior to that time the parasite had been nom-ished by its ovm. 

 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. ^ flowers ; 3. ^ flowers 

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

 ' Decaisne). 



Fig. DXXIV. 



