142 



SCIENCE-GOSSIP. 



2. Position of Flowers. — After the arrange- 

 ment, of leaves on the stem nothing is of so much 

 importance to the character of the tree as the 

 position of the flowers. A leafy shoot can go on 

 lengthening indefinitely, but all lengthening is at 

 an end at the point where a flower is formed. All 

 further growth from that point must take place in 

 a new direction, and hence the importance to our 

 subject of the position of the flowers. The flower, 

 or group of flowers, constituting the inflorescence, 

 may be either terminal or lateral : terminal, as 

 in the sycamore and maple, which leads to a bushy 

 growth ; lateral, as in the elm and ash, in which 

 case the branches lengthen year after year from 

 the terminal bud. Then the inflorescence may 

 spring immediately from the ripened wood of last 

 year, as in the elm and ash, and in many willows ; 

 or else it may spring from the green and growing 

 shoot of the present season, as in the lime. In all 

 cases, however, there is no further leafy growth 

 where the bud has given rise to flowers. In the 

 lime-tree, however, and in the case of the fertile 

 flowers of the oak, there is generally formed a 

 fresh leaf-bud by the side of the peduncle, which 

 leaf-bud will give rise to a branchlet in the follow- 

 ing season. Thus there will be no interference 

 with the order of the branching as originally 

 determined by the position of the leaves. 



3. Angle of Growth. — The angle which each 

 branch makes with the stem or branch from which 

 it springs will be found to van- with the species. 

 There is, speaking generally, for each kind of tree 

 a certain normal angle at which the branches are 

 given off, producing an effect on the general 

 appearance and character of the tree which we 

 can recognise perhaps even better in winter than 

 in summer. This normal angle is best seen in the 

 younger branches and spray wood. Not only do 

 the larger limbs become bent downwards by the 

 weight of branches and foliage, but in various 

 cases it would seem that the earlier and leading 

 branches of the tree have a greater tendency to 

 ascend and approach the main stem, thus making 

 a smaller angle with it above the point of junction, 

 than do the smaller branchlets with the branches 

 from which the}- spring. In the case of the ash, 

 the branches show a tendency to come off at an 

 angle of about 40^ with the stem above then- 

 point of departure ; the younger branches approxi- 

 mate more closely than this. In the wych-elm the 

 ultimate branchlets make, generally speaking, an 

 angle larger than a right-angle with their parent 

 branch. The main branches seem, in the first 

 instance, to come off at a smaller angle, but they 

 very frequently, at the distance of a foot or 

 two from the stem, bscome bent downward and 

 drooping. 



Extreme examples of these differences in angle 

 are seen in the Lombard}- poplar on the one hand, 



with its upright branches, and the weeping ash, or 

 weeping elm, of nursery gardens and shrubberies, 

 on the other hand. 



Besides the angle at which a branch approaches 

 or diverges from the main stem, it is sometimes the 

 case that the branches are set on obliquely, not 

 following the direction of a straight line from the 

 centre of the parent stem or branch through their 

 point of origin, but rather the direction of a 

 tangent to some point in the circumference of the 

 stem. This is seen in the crack willow (Salix 

 fragilis, L.), as was pointed out by Smith in " The 

 English Flora." 



I may also draw attention to the peculiar 

 directions assumed by the lesser branches in 

 different trees, or even in different individuals of 

 the same kind of tree. These branchlets often 

 choose to assume a direction of their own instead 

 of that taken by the branches from which they 

 spring. In vigorous-growing forms of the wych- 

 elm (Ulmns montana) for instance, the lateral 

 branchlets generally preserve a horizontal growth ; 

 in the more slender-growing forms of the same tree 

 they are often pendulous, whilst in the small-leafed 

 elm (Ulmns campestvis) they show a strong tendency 

 to turn upwards towards the sky, and this, as will 

 hereafter be shown, has an important bearing on 

 the general outline and aspect of the tree. No 

 cause has, so far as I know, been assigned for these 

 differences, nor for the even more strongly marked 

 tendency to bend downwards which we see in the 

 weeping ash and weeping elm. 



4. Length of Internode. — The comparative 

 length of the internode, or space between leaf and 

 leaf, affects also the aspect of a tree, causing, as it 

 does, the leaves, and consequently the branches, 

 to be more crowded in one case and more widely 

 separated in another. Thus the length of the 

 internode or joint in the ash is, in the vigorous, 

 quickly-grown branches, which are only bearing 

 leaves, as much as three inches ; in the branchlets, 

 which produce flowers, it is much shorter. 



In the beech, the distance from leaf to leaf 

 varies from one inch to two and a quarter inches, 

 In the wych-elm I have found it vary from five- 

 eighths of an inch to one and three-quarter inches ; 

 in the small-leafed elm, I believe it is commonly 

 less than this. In the sycamore it varies from 

 three-quarters of an inch in the weaker shoots to 

 two and three-quarter inches in the more luxuriant 

 ones. In the maple I have found it from half an inch 

 or less to one and a half inches. 



5. Comparative Thickness or Diameter of 

 Yearly Shoots. — There is much variation in this 

 respect. In the beech, for example, the young 

 shoots of the year are often only one-sixteenth and 

 rarely more than one-eighth of an inch in diameter. 

 In the ash they are very commonly from one-quarter 

 to three-eighths of an inch. The result is the stiff 



