INFLUENCE OF THE PLUM-STOCK ON THE APRICOT. 275 



ordinary method of budding upon plum-stocks ; and that the rapidity of 

 their growth will amply compensate for the small size at which it will be 

 expedient to plant them. An opinion prevails amongst gardeners, that 

 such trees will prove very short-lived ; in opposition to this, I have 

 nothing further to say, than that I have plants of more than twelve years 

 old, one of fourteen years old, which certainly show no disposition to die, 

 nor any appearance of having grown old. 



LIII. AN ACCOUNT OF SOME MULE PLANTS. 



[Read before the HORTICULTURAL SOCIETY, May 6th, 1823.] 



THE excessive rarity of mule plants in a perfectly wild state (if in such 

 they exist at all), and the facility with which they are in many cases 

 obtained in the garden, seem to countenance the opinion which is enter- 

 tained by many botanists, that plants of different species do not readily 

 breed with each other, till their natural habits have been broken and 

 changed by the operation of culture through some successive generations. 

 Vegetable mules are, however, never produced except under circumstances 

 which rarely, if ever, occur in a perfectly natural state ; for experiment 

 has satisfied me, that not only the pollen of the alien species must be 

 introduced at the proper period, but also, that the natural pollen must 

 be kept away not only at that precise period, but generally, for several 

 succeeding days afterwards : also, and even under the most favourable 

 circumstances, I have never succeeded in obtaining mules, unless the plant, 

 or a considerable branch of a fruit tree, has been reduced to the necessity 

 of nourishing mule offspring, or none. When the later blossoms on a fruit 

 tree were suffered to remain, such branch either threw off the fruit which 

 would have afforded mule plants, or the natural pollen was found to have 

 been subsequently introduced by insects or winds, and to have annihilated 

 the operation of that obtained from the plant of another species. Not 

 improbably some erroneous conclusions may also have been drawn, owing 

 to varieties of permanent habits into which different species of plants 

 have sported, under the influence of different soils and climates, in a 

 perfectly natural state, having been mistaken for originally distinct 

 species; for 1 perfectly agree with Mr. Herbert*, in thinking that the 

 number of species of plants, which came immediately from the hand of 



* Horticultural Transactions, Vol. IV. page 16. 



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