
TRANSACTIONS OF THE SECTIONS. 67 
the plant as constructed on one model throughout. Speaking in this paper of reticu- 
lated leaved plants, he showed that there is a correspondence between the disposition 
of the branches along the axis and the distribution of the venation of the leaf. 
(1.) In some plants the lateral branches are disposed pretty equally along the 
axis, whereas in others a number are gathered together at one point, and the plant 
becomes verticillate or whorled. Now, he found that wherever the branches are 
whorled, either the leaves of the plant, as in the rhododendron, dlchemilla alpina, 
common barberry, broom, laburnum, marsh trefoil, or the veins of the individual 
leaf, as in the common sycamore, dlchemilla vulgaris, currant, gooseberry, guelder 
rose, geranium, maple, are also whorled. 
(2.) When a leaf has a petiole, the tree has its trunk unbranched at the base (as in 
the case of the sycamore, apple, &c.), and when the leaf has no petiole, the trunk 
is branched from the root, as in our common ornamental lawn shrubs—the bay 
laurel, holly, box, &c. 
(3.) He proceeded to show further, that the angle at which the branches go off 
from the axis is the same as that at which the side veins go off from the main veins. 
His observations during the past summer had been chiefly directed to this point. 
He made the measurements by means of a graduated semicircle with a moveable 
index. In these measurements he took the angle formed by the main lateral branches 
with the axis, and by the main lateral veins with the midrib. The angle of the 
veins of the leaf is easily taken. It is more difficult to determine the natural angle 
of the branches, inasmuch as the direction of the branch may be altered by a variety 
of circumstances, as by winds, its own weight, &c. Still, there is evidently anormal 
angle for each species of plant, which may he ascertained by taking the average of 
a number of measurements of a freely growing branch. He had measured in all 
about 210 species of plants, and found the angle of the branch and of the vein to 
correspond. He produced a tabulated statement of these 210 plants, and called 
the special attention of the Section to several of them, as under the letter A. 
Plants with Woody Structure. Angle of vein 
and branch. 
° ° 
Alaternus, very short petiole and branched to near root 50 
Alder, short petiole and short unbranched trunk ..... 50 
Andromeda speciosa. .......-. aowenols aysiie seh ciao 
Apple, has petiole and unbranched trunk ....... 2+» 45 
Arbutus, very little petiole, or unbranched TUUDK sop endycs 55 
Azalea,no petioie, and no unbranched trunk, leaves and 
branches; WHOM ho, «sy af <0: aieprey ojalishy soe, sok poy ska claagepien/GO 
Native Herbaceous Plants. 
Achillea millefolium ..... custiiioss sete Seatant ens sgh aD 
Achillea ptarmica .......---- Pees fastener se OOO 
Arctostaphylos Uva Ursi......-...--.+-. eerten et 35—38 
Agrimonia eupatoria..,......-.. qloronaRe arcane +. 35 
Alchemilla vulgaris, main veins whorl, and leaves an 
branches whorl ..........--- Sr ihe, Banh hd seca atiee 37 
Alchemilla alpina, leaflets whorl, a also flowerstalks, 
and'leafstalks . 2.2300. oe. tl ee ee seca iceparon a cx4 
Angelica sylvestris ........0- ee eee eee eee eee 40 
Anthriscus sylvestris... 2.0.22. eee ee eee ees . 40 
Arctium lappa, angle decreases from base.......-.-+ 48—40 
Apargia autummalis ........ 2.022 e cere tree ees 50 
Atriplex patula......... Do cue Oar Beka wate sa) eed 
Alisma plantago, has whorled veins and whorled leafstalks 60 
(4.) He had also observed that the curve of the branch seems to be the same as 
the curve of the vein. 
These observations seem to show that there is a morphological analogy between 
the ramification and venation of reticulated leaved plants. Though he could not 
enter on the subject at present, he believed that there was a similar unity running 
5% 
