12 THE MISTLETOE PEST IN THE SOUTHWEST. 



numbers by these birds either in their excrement or by being wiped 

 from the beak against a branch in the birds' efforts to remove the 

 adhesive pulp. In either case the pulp still remaining about the 

 seed causes it to stick to the branch and by drying to become firmly 

 pasted there. It is the conclusion of most observers that the mocking 

 bird is the chief distributer of mistletoe seed, but perhaps the cedar 

 birds actually distribute more, for in March and April these birds 

 appear in flocks of hundreds in search of berry mast — especially hack- 

 berries — and during the brief visits of a few days or a week or two all 

 the berry-laden trees are visited repeatedly until the berries are gone. 

 During these flights, mistletoe berries are also eaten, though probably 

 not much noticed until the hackberry crop is exhausted. Robins 

 also are reported to be common distributers of mistletoe seed. In 

 the vicinity of Austin large flocks of robins spend the winter, or part 

 of it, in the cedar brakes, where they feed largely on cedar mast; but 

 at times they appear in numbers about farmyards and in towns, 

 feeding upon hackberries, and during these visits also upon mistletoe 

 berries. 



Mistletoe is, however, not wholly dependent upon birds for the 

 distribution of its seeds, for as the spring advances and the berries 

 grow softer they fall away easily, becoming crushed and adhering 

 to the branch below. Especially are they beaten off in heavy 

 downpours of rain and washed against the branches, where they are 

 left adhering in favorable situations for germination. The char- 

 acter of infection of certain cedar elm trees illustrates very plainly 

 this method of infection. Pendent branches become laden with 

 bunches of mistletoe from base to tip, showing how the seeds were 

 washed down the branch during a heavy rainfall. 



STRUCTURE AND VITALITY OF THE SEED. 



Of course, mistletoe seeds become planted in the ways just de- 

 scribed in all sorts of places and in favorable weather are induced 

 to germinate in almost any situation — upon branches, upon the 

 main trunk, upon leaves, dead twigs, fences, and even upon mis- 

 tletoe itself — but the only situation in which there is any prospect 

 of this germination resulting in the establishment of a mistletoe 

 plant is, as previously stated, upon the living branch or trunk of 

 a tree, and only then where the bark is thin or cleft, or otherwise 

 in a condition to permit the penetration of the root axis or sinker 

 of the seedling. In any event, the bark or epidermis of a tree would 

 seem to be barren soil, since it dries so quickly. This is particu- 

 larly true in central Texas and westward, where the atmosphere 

 is habitually dry. The seeds have need to be strongly drought 

 resistant, and this quality they seem to possess in a marked degree. 



166 



