214 Transactiona. — Botany. 



winds small twigs and limbs are broken from the older trees 

 and float to and lodge on the banks, where they readily root 

 and grow into large trees in a few years. When travelling 

 through Wakanui across the open plain the irregular paie- 

 green line of high beautiful willows produces an admirable 

 contrast to the small plantations of sombre evergreen pines 

 around the settlers' homes. From its artificial mode of dis- 

 persal and propagation I have not included this willow in my 

 list of naturalised plants. The basket-willow (S. rubra) and 

 the golden willow (S. vitellina) propagate likewise, bus they 

 are not so numerous as is the weeping willow. 



As previously stated, several species of naturalised plants 

 displayed great vigour and spread rapidly for a few years 

 after their introduction, when their vigour declined and their 

 numbers diminished and became rare or disappeared from 

 large areas where formerly they were abundant. The dis- 

 appearance of a large number of species is due to severe 

 climatic conditions occurring at intervals of several years on 

 the Canterbury Plains. The protracted drought between 1895 

 and 1898 very materially checked the progress and reduced 

 the numbers of many species of naturalised plants in the 

 county. Previous to those years large masses of buckwheat 

 (Fagopyrum esculcntum, Moench.) grew annually along the 

 railway banks and sides, but I have not observed a single 

 plant since the close of the drought. Several other species 

 that were killed off certain areas by the drought have not up 

 to the present time been able tore-establish themselves in the 

 same numbers as formerly. 



During the last five years of more or less cool wet weather 

 at all seasons Centaurea nigra and Onopordon acanthiuvi have 

 dispersed rapidly. In the autumn, when the seed is ripe, the 

 plants are visited by large flocks of goldfinches, who attack 

 ihe flower-heads and scatter the seed in all directions. 

 Echium vulgare, which is fertilised by humble-bees, is also in- 

 creasing rapidly. Diplotaxis muralis and a tall-growing 

 handsome-flowered Nasturtium which I have been unable to 

 identify were first collected four years ago, but they now 

 occur in several districts. Two plants of the teasel thistle 

 {Dipsacus sylvestris) were sent to me last year from Waterton, 

 but I have not collected it nor heard of its occurrence else- 

 where in the county. The present great demand for all 

 classes of arable land, and the extensive ploughing by im- 

 proved methods proceeding annually, together with the use of 

 strong artificial manures and vastly increasing flocks, will 

 rapidly check and diminish the numbers of both native and 

 naturalised plants excepting on waste places. A sketch of 

 their introduction and progress in a given area during the last 

 half-century will enable botanists of the future to note and 



