Q6 



KNOWLEDGE 



[Mabch, 1903. 



best known sjtmus of the sub-order, and iueludos a number 

 of shrubs and herbs that are i,'rown in gardens for tlie 

 sake of their graceful foliage aiid pretty clusters of white 

 or red flowers. The Dri/adeie derive their name from the 

 genus Dri/as, of which one species belongs to our 

 <H)untrv — the beautiful little alpine plant D. odopetala, 

 or Mountain Aveus. Here also belongs the genus 

 Potentilla, famed for the number of beautiful herbaceous 

 s]>ecies which it includes. The best known genera, however, 

 are Fraijaria and Ruhns, the former of which yields the 

 luscious Strawberry, the latter the Raspberry and 

 BlackbcuTy. In most of the other species tlie fruit is 

 quite dry. Poteriem forms a curious degraded group of 

 Rosaceie, with flowers strangely different from those, such 

 as Dog Rose, Apple Blossom, Hawthoi-n, or Bramble, 

 which we associate with the Order. The gay cup-shaped 

 corolla which gives beauty and character to the flower 

 of most of the Bosaceie, is in many plants of this 

 group entirely suppressed. The Poteriem are like several 

 of the preceding groups found chiefly in the North- 

 Temperate zone, but its largest genus, Cliffortia, is 

 characteristically South African. The sub-order Bosem 

 includes only the genus Hosa. The glorious arrav of 

 cultivated Roses are the offspring of a few wild foreign 

 species, notably B. centifolia, B. gallica, B. alba, B. indica, 

 li. henyalensis ; and the British B. amensis (Trailing Dog 

 Rose), and B. ruhlginosa (Sweet Briar.) The Roses are 

 essentially a North-Temperate group, a few extending 

 southward into the tropics, but none reaching the South- 

 Temperate regions. Lastly there is the sub-order Pomacese, 

 so called from the characteristic fleshy fruit or -pome, 

 which is borne by its membei's, such as the Apple and 

 Pear. Sometimes the fruit is stony, as in the Hawthorn, 

 but more frequently coriaceous, as is found in the Quince, 

 Pear and Apple. 



Let us now consider the British species of Basacex, and 

 note their number, distribution, and the various points of 

 interest connected with them. There is a difficulty in 

 stating the total number of British species, owing to the 

 varying value that has by different botanists been allowed 

 to the puzzling series of Brambles, to which may be added 

 the Roses. Thus while Hooker (Student's Flora) reduces 

 the British species to 45, by lumping the fruticose 

 Brambles imder Bttbus fruticosus, L., and treating certain 

 other segrates similarly, the London Catalogue lists over 

 150 species, by allovring specific rank to a large number 

 of Brambles and other segregates. The British Rosacem 

 are, speaking very generally, herbs, shrubs, or small 

 trees with a wide distribution, with graceful forms and 

 pretty fragrant flowers, white and yellow being the pre- 

 vailing tints. Of the sub-order Pruneie, we have the 

 genus Pruuus alone, represented by several species. The 

 tough black-stemmed Blackthorn or Sloe (P. spinosa) 

 with its thoj-ny branches and bitter fruit, is well known. 

 The closely allied P. insititia (Bullace), and P. domestica 

 (Wild Plum) are more plum-like small trees, and doubtfully 

 indigenous. Then we have three species of Cherry. 

 P. Cerasus (Dwarf Cherry) has bitter red fruit, and the 

 larger P. Avium (the common Wild Cherrj') has also 

 bitter fruit, which is red or black The latter is the origin 

 of our many garden Cherries. The Bird Cherry (P. Padus) 

 bears its pretty blossoms, not in umbel-like clusters like 

 the last two, but in graceful racemes. The fruit is small, 

 black, and bitter. Of the three Cherries, P. Cerasus alone 

 has a restricted range in our islands, being distinctly 

 southern. 



The Spiraiaceie are, like the Prunex, represented in these 

 countries by only one genus, Spirxa, which numbers but 

 two native species. The delightful Meadow-Sweet (S. 

 Ubuaria) needs no description. Its bold growth, its 



striking foliage, deep green above, white beneath, with 

 deeply-cut pinna; and curious little leaflets Ixitween, and 

 its cloudy masses of creamy fragrant flowers, are one of 

 the dearest features of our English meadows. The other 

 native sj)ocies, the Dropwort (S. Filipendiila), is an equally 

 pretty, though less striking plant, with l)eautifully cut 

 ])innate leaves and white flowers. The roots liear peculiar 

 conspicuous knobs. While in Great Britain it is widely 

 spread, it has in Ireland a peculiar limited range, occurring 

 in great abundance over a small portion of Clare and 

 Gal way, and there only. 



Turning to the Dri/adea;, we find ourselves face to face 

 with the bewildering Brambles. We can easily dis- 

 criminate the Raspberry (Buhus Idveus) with its pinnate 

 leaves and red fruit. Its stems are upright and covered 

 wdth weak prickles, and it does not attempt to climb. 

 Then we have two herbaceous species, also easily 

 recognized — the Stone Bramble {B. saxatilis), with far- 

 creeping slender barren stems and short upright flowering 

 ones, which eventually bear red fruit ; and the small Alpine 

 Cloud-berry (E. Chamxworus), with entire Lady's-mantle- 

 like leaves and orange fruit. And then remains the 

 Blackberry group. These are interesting to us as being 

 good examples of "hook-climbers." Their stems are 

 furnished with very strong hooked prickles — remarkable 

 structures, arising, like hairs, from the skin, not from the 

 wood, as do, for instance, the thorns of the Hawthorn. 

 By aid of these prickles, the Brambles supjiort themselves 

 amid tangled thickets, and may be often seen bursting 

 into blossom 10 or 1.5 feet up in the air. It is interesting 

 to note that the long arching stems in autumn, when their 

 growth is nearly over, frequently again seek the ground. 



Fm. 2.— Rooted tip of Bramble-shoot. 



and their tips root themselves firmly in the soil. Next 

 year the shoot produces flower and fruit, and ciies. But 

 from the rooted tip proceeds a fresh plant, which in tura 

 loops away and produces new offspring far from the parent. 

 The plant" may in this manner travel forward at the rate 

 of 20 feet or more per year, and may cross obstacles such 

 as a ten-foot wall in a single season.* These Brambles were 

 grouped by Linnaeus under one species (Buhus/ruticosus). 

 But when we look into them, great differences are noticeable 

 as regards growth, habit, colour, texture, shape, and size of 

 leaf and flower; and in the form, number, and arrangement of 

 prickles. Hence numerous other names have been bestowed 

 on apparently distinct forms, and the process has gone on 

 until the latest work on the British Brambles lists one 

 hundred " species " under Linnaeus' B. fruticosus, with 

 numerous sub-species and varieties. It is difficult to explain 

 such a comphcated tangle of closely allied forms. The 

 most nearly related genera, such as Potentilla, display no 



* See Iris/i Naturalist, March, 1897, a.nd February', 1902. 



