256 SCIENCE OF AGRICULTURE. Part II. 



plum of the ancients is perhaps not yet ascertained. Bonnet has further remarked that the ripe ears of 

 corn, which bend with the weight of grain, scarcely ever incline to the north, but always less or more to 

 the south ; of the accuracy of which remark any one may easily satisfy himself by looking at a field of 

 wheat ready for the sickle; he will find the whole mass of ears nodding, as if with one consent, to the 

 south. Tlie cause of the phenomenon has been supposed to be a contraction of tlie fibres of the stem or 

 flower-stalk on the side exposed to the sun ; and this contraction has been thought by De la Hire and 

 Dr. Hales to be occasioned by an excess of transpiration on the sunny side ; which is probably the fact, 

 though there seems upon the principle to be some difficulty in accounting for its returning at night; 

 because if you say that the contracted side expands and relaxes by moisture, what is it tliat contracts the 

 side that was relaxed in the day? The moisture, of which it is no doubt still full, would counteract the 

 contraction of its fibres, and prevent it from resuming its former position in the morning. 



1659. Heat as well as light acts also as a powerful stimulus to the exertions of the 

 vital principle. This has been already shown in treating of the process of geniiination ; 

 but the same thing is observable with regard to the developement and maturation of the 

 leaves, flower, and fruit ; for although all plants produce their leaves, flower, and fruit 

 annually, yet they do not all produce them at the same period or season. This forms 

 the foundation of what Linnaeus has called the Calenddrium Florce, including a view of 

 the several periods of the frondescence and efflorescence of plants, together with those of 

 the maturation of the fruit. 



1660. Frondescence. It must be plain to every observer, that all plants do not protrude their leaves at 

 the same season, and that even of such as do protrude them in the same season, some are earlier and some 

 later. The honeysucicle protrudes them in the month of January ; the gooseberry, currant, and elder, 

 in the end of February, or the beginning of March ; the willow, elm, and hme tree, in April ; and the 

 Platanus, oak, and ash, which are always the latest among trees, in the beginning or towards the middle 

 of May. Many annuals do not come up till after the summer solstice ; and many mosses not till after 

 the commencement of winter. This gradual and successive unfolding of the leaves of diflTerent plants 

 seems to arise from the peculiar susceptibility of the species to the action of heat, as requiring a greater 

 or less degree of it to give the proper stimulus to the vital principle. But a great many circumstances 

 will always concur to render the time of the unfolding of the leaves somewhat irregular ; because the 

 mildness of the season is by no means uniform at the same period of advancement ; and because the 

 leafing of the plant depends upon the peculiar degree of temperature, and not upon the return of a 



Particular day of the year. Hence it has been thought that no rule could be so good for directing the 

 usbandman in the sowing of his several sorts of grain, as the leafing of such species of trees as might be 

 found by observation to correspond best to each sort of grain respectively, in the degree of temperature 

 required. Linnseus (Stillingfleet informs us> instituted some observations on the subject about the year 

 17o0, with a view chiefly to ascertain the time proper for the sowing of barley in Sweden ; he regarded 

 the leafing of the birch tree as being the best indication for that grain, and recommended the institution 

 of similar observations with regard to other sorts of grain, upon the grounds of its great importance to 

 the husbandman, who may be said to attend to it in a manner instinctively; but as all the trees of the 

 same species do not come into leaf precisely at the same time, and as the weather may alter even after 

 the most promising indications, no guide, n.atural or artificial, can be absolutely dejjcnded on with a view 

 to future results. 



1661. Efflorescence. The flowering of the plant, like the leafing, seems to depend upon the degree of 

 temperature induced by the returning spring, as the flowers are also protruded pretty regularly at the same 

 successive periods of the season. The mezereon and snowdrop protrude their flowers in February; the 

 primrose in the month of March ; the cowslip in April; the great mass of plants in May and June ; many 

 in July, August, and September ; some not till the month of October, as the meadow saffron ; and some 

 not till the approach or middle of winter, as the laurustinus and arbutus. Such at least is the period of 

 their flowering in this country; but in warmer climates they are earlier, and in colder climates they are 

 later. Between the tropics, where the degree of heat is always high, it often happens that plants will 

 flower more than once in the year ; because they do not there require to wait till the temperature is 

 raised to a certain height, but merely till the developement of their parts can be effected in the regular 

 operation of nature, under a temperature already sufficient. For the greater part, however, they flower 

 during our summer, though plants in opposite hemispheres flower in opposite seasons. But in all climates 

 the time of flowering depends also much on the altitude of place, as well as on other causes affecting 

 the degree of heat. Hence plants occupying the polar regions, and plants occupying the tops of the high 

 mountains of southern latitudes, are in flower at the same season ; and hence the same flowers are later 

 in opening in North America than in the same latitudes in Europe, because the surface of the earth is 

 higher, or the winters more severe. 



1662. Maturation of the fruit. Plants exhibit as much diversity in the warmth and length of time 

 necessary to mature their fruit, as in their frondescence and flowering; but the plant that flowers the 

 soonest does not always ripen its fruit the soonest. The hazel tree, which blows in February, does not 

 ripen its fruit till autumn ; while the cherry, which does not blow till May, ripens its fruit in June. It 

 may be regarded, however, as the general rule, that if a plant blows in spring, it ripens its fruit in sum- 

 mer, as in the case of the currant and gooseberry ; if it blows in summer, it ripens its fruit in autumn, as 

 in the case of the vine ; and if it blows in autumn, it ripens its fruit in winter : but the meadow-saffron, 

 which blows in the autumn, does not ripen its fruit till the succeeding spring. 



1 663. Such are the primary facts on which a Calenddrium Flbree should be founded. 

 Tliey have not hitherto been minutely attended to by botanists; and perhaps their 

 importance is not quite so great as has been generally supposed; but they are at any 

 rate suflSciently striking to have attracted the notice even of savages. Some tribes of 

 American Indians act upon the very principle suggested by Linnajus, and plant their 

 corn when the wild plum blooms, or when the leaves of the oak are about as large as a 

 squirrel's ears. The names of some of their months are also designated from the state 

 of vegetation. One is called the budding month, and another the flowering month ; 

 one the strawberry month, and another the mulberry month ; and the autumn is desig- 

 nated by a term signifying the fall of the leaf. Thus the proposed nomenclature of the 

 French for the months and seasons was founded in nature as well as in reason. 



1664. Cold. As the elevation of temperature induced.by the heat of summer is es- 

 sential to the full exertion of the energies of the vital principle, so the depression of 

 temperature consequent upon the colds of winter has been thought to suspend the ex- 

 ertion of the vital energies altogether. But this opinion is evidently founded on a mistake, 

 as is proved by the example of those plants which protrude their leaves and flowers in 



