22 



The Canadian Field-Naturalist 



[Vol. XXXVI 



shown in Fig. No. 1. Tlie huge limbs stretching 

 out in all directions prove that the tree must hava 

 had plenty of room in the past. The young 

 growth of Douglas fir surrounding the arbutus is 

 of recent origin. 



HELIOTROPIC RESPONSE. 



When the arbutus is compelled to strive for light 

 in competition with other trees it shows the 

 characteristics of positive heliotropism to a 

 degree surpassing most of its competitors. It has 

 learned to dodge and looks as if it were trying to 

 avoid contact wth its neighbors. If the sur- 

 rounding trees are destroyed, then the arbutus, 

 curved and bent over, forms a unique feature of 

 the landscape. In Fig. No. 2 the curved arbutus 

 is a good example of the heliotropic response due 

 to light contest with other trees, since removed. 

 The characteristic of positive heliotropism seems 

 to obtain to a similar degrae in arbutus, wherever 

 it is found. Prof. Jepson, ("The Trees of Cali- 



FiG. 2. HELIOTROPISM, Arbutus Menziessii, Pursh 



Example of curved stem of arbutus due to former contest for light, 

 with other trees since destroyed. Many of these odd shaped trees are to 

 be found. Locality, Scenic Drive, Mount Douglas ("Cedar Hill") Park, 

 Victoria district, Vancouver Island, B.C. Illustration kindly loaned by the 

 Victoria and Island Publicity Bureau, Victoria, B.C. 



fornia," Willis Linn Jepson, Ph.D., Cunningham 

 Curtis and Welch, San Francisco, 1909, p. 208) 

 referring to the phenomenon says: 



Madroiia is rarely symmetrical and 

 the older the tree the more unsymm^t- 

 rical as a rule. This is notably the 

 case in the Mendocino and Humbolt 

 woods, where it is invariably pushed 

 to one side when in light competition 

 with Douglas Fir or Tan Oak. Huge 

 Madrofia crowns, wholly one-sided, are 

 frequently met with; sometimes the 

 aggressive companion trees disappear 

 and leave these irregular Madronas 

 standing alone. Very frequently one 

 finds a long trunk curving out of the 

 perpendicular 20 or 30 feet and up 

 60 or 70 feet to a wisp of a crown occupy- 

 ing a very small area of the forest canopy. 

 Such trees are remarkable for their 

 curving and often huge trunks, 

 which are commonly very tall 

 and often flattened contrary to 

 the direction of the curve. 

 The curved and bent specimens of 

 Arbutus unedo L. on Dinis Island, Kil- 

 larney, Ireland, figured in Plate No. 157 

 of "The Trees of Great Britain and 

 Ireland," (John Henry Elwes, F.R.S., 

 and Augustine Henry, M.A., Vol. Ill, 

 Edinburgh, 1908) are presumably the 

 result of heliotropic bending. The 

 curves may, however, be caused by 

 wind. 



CONTINUITY IN FLOWERING. 



The flowering and fruiting of the ar- 

 butus form interesting phases of its life 

 history. 



Sometimes the trees of a whole dis- 

 trict will totally discontinue production 

 of floral buds for several seasons, or, in 

 the same grove, some of the trees may 

 cease while others continue vigorous 

 production. 



During the years that arbutus does 

 carry on activity in flowering the con- 

 tinuity of the operation is remarkable. 

 Without any marked resting period, from 

 early spring to late autumn flowering 

 may be found in every stage; buds, 

 blossoms, and berries. During the win- 

 ter months generally from about No- 

 vember to March no fresh buds develop 

 and the late buds do not blossom, though 

 they continue to increase in size and 

 advance another stage toward the blos- 

 som throughout every mild spell, until 



