HTSTEROPHYTA. 501 



Myzodendron is a reduced form of the Santalaceaa ; the $ -flowers are without 

 perianth ; the perianth of the ? -flower is 3-rnerous. About 7 species ; S. Am ; 

 parasitic on a Beech (Nothofagus). The fruit has 3 feathery brushes, alternat- 

 ing with the lobes of the stigma, which serve as flying organs and to attach 

 the fruits to a branch (Fig. 541), the brushes twining round as soon as they come 

 iu contact with it. There is only 1 seed in the fruit, which germinates by a long, 

 negatively heliotropic hypocotyl, and is attached by a radicle moditied into an 

 haustorium. 



Order 3. Loranthaceae (Mistletoes). Plants containing 

 chlorophyll which are parasites on trees, and most frequently 

 have opposite, simple, entire leaves and regular, epigynous, 

 often unisexual, 2- or 3-merous flowers, with single or double 

 perianth. Stamens equal in number and opposite to the perianth- 

 leaves, free, or in varying degrees united to one another. The 

 inferior ovary is constructed as in the Santalacere, the ovules being 

 situated on a low, free, centrally-placed placenta, but the placenta 

 and ovules unite with the wall of the ovary into one connected, paren- 

 chymatoiis mass, in which the embryo-sacs are imbedded. Only 1 

 (less frequently 2-3) of the 1-6 embryo-sacs is fertile. The num- 

 ber of the carpels however varies. The fruit is a I-seeded berry, 

 whose inner layer is changed into a tough slimy mass (bird-lime), 

 which serves to attach the fruits to other plants. 



The two groups, Loranthoidece and Viscoidea, are distinguished by the fact 

 that the former has a distinct " calyculus," i.e. an entire or lobed, or dentate 

 swelling on the receptacle below the perianth. The majority of the Loran- 

 thoideae have a petaloid perianth ; in all the Viscoideas, on ths other hand, it is 

 sepaloid. 



The Mistletoe (Viscum album, Fig. 542) is a native, evergreen 

 plant which may be found growing on almost any of our trees 

 (sometimes on the Oak), and, like other Loranthacege, it produces 

 swellings of the affected branches. Its spherical white berries (Fig. 

 542 A) enclose (1-) 2-3 green embryos; they are eaten by birds (especially 

 Thrushes), and are partly sown with their excrement, partly struck or brushed 

 off the branches of the trees, the seed being enclosed, at maturity, by viscin, i.e. 

 " bird-lime." The seeds may also germinate on the branches, without having first 

 passed through the alimentary canal of the birds. On germination, the hypo- 

 cotyl-axis first appears, as in Fig. 541, and bends towards the branch ; the apex 

 of the root then broadens, and forms at the end a disc-like haustorium, from the 

 centre of which a root-like body grows through the bark into the wood, and 

 ramifies between the bark and wood. Suckers are developed on the root like 

 strands which are formed in this manner, without, however, having a root-cap ; 

 they are green, and penetrate the wood by the medullary rays (Fig. 542 C). 

 Adventitious buds may also be developed from the root-like strands which break 



