16 THE LORANTIIACEAE OF AUSTRALIA^ i., 



applied the name "aggressive," and to the second "defensive" attachment, or 

 union. 



It is not my intention to go into details, as the subject needs careful and 

 critical investigation; all I propose to do is to draw attention to it. 



Loranthus GaudicUaudi provides a good example for the ball-like union. 

 The fusiform swelling is the result of the division and creeping nature of the 

 radicle as it penetrates the host, causing it to swell into a cylindrical body, as 

 seen in P. BidwilUi. This form is invariably followed by adventitious roots 

 which soon make their appearance, relieve the radicle by effecting an eai-ly 

 union with the host, and thus lessen the growth at the point of attachment, 

 rarely if ever reaching the dimension of the ball-like union. Sometimes the 

 adventitious roots fonn a conspicuous swelling at the union, and increase in 

 size, ultimately forming the main stem, as seen in some plants of P. celastroides. 



Under "Origin" (p. 6) 1 drew attention to the adventitious roots of 

 Loranthus, which appear to have impressed some observers with the idea that 

 it was at one time a climbing plant, and through evolutionary changes had dis- 

 pensed with the soil as a means of existence, and instead acquired the habit of 

 appropriating the bark and sap of various plants to perfect itself, just as its 

 hosts utilise the soil in the process of their development and reproduction. 



It will be admitted that those species possessing adventitious roots appear 

 to throw some light upon their origin, as suggested by Meyer and Keeble, and 

 therefore, are singulai'ly interesting on that account. 



It might be assumed that the balMike growth, or union free from aerial 

 roots, belongs to the oldest species, as it demonstrates that the parasites, through 

 evolution, have thrown off what is usually accepted as one of their primary 

 chai-acters, and have to depend upon a single attachment. If that is so, they 

 therefore make the fullest use of the sun's rays in the assimilation and reten- 

 tion of essential foods: much of their food no doubt consists of atmospheric 

 moisture and inorganic compounds, and they are to a great extent self sup- 

 porting. This single adhesion is also more suggestive of xerophytic nature 

 than support by adventitious roots; it is not nearly as destructive to vegetation, 

 and is easily eradicated. 



None of the Australian Loranthaceas throw out runners beneath the cortex 

 of the host like the European mistletoe, Viscum album L., and they are, on that 

 account, much easier to eradicate without doing any serious damage to the host. 



The following species develop a ball-like union: — L. pendulus, L. congener, 

 L. Miquelii, L, Gaudichaudi, L. miraculosus and varieties, L. No. 15, n.sp., L. 

 Unophyllus, L. grandibracteus, L. Exocarpi and varieties (aggressive), L. Quan- 

 dang and var. Bancrofti, L. No. 21, n.sp., L. No. 21, n.sp., L. ferruginiflonis. L. 

 gibberulus, L. Murrayi, L. No. 32, n.sp., L. Nestor. 



Species with a fusiform union or not definitely ball-like: — P. myrtif alius, 

 P. Bidivillii, P. celastroides [Sometimes ball-like (defensive) type when parasite 

 on Platanus orientalis'\, P. eucalyptifolius, L. vitellinus [Sometimes ball-like 

 (aggressive) when on smooth-barked trees like Angophora lanceolata. This 

 species m many eases throws out one or two adventitious roots which soon 

 ■develop haustoria, causing the wood "of the host of rough-barked trees to expand 

 around them in raised globular excrescences, which, as they gi-ow, remove the 

 adventitious root further away from the host, which does not increase in size, 

 and IS soon surpassed in thickness by the main branches of the parasite], L. No. 

 •23, n.sp., L. alyxifolius, L. dictyophlebus [Growth similar to that of L. vitellinus], 

 L. hiangidatm. 



