162 



KNOWLEDGE 



[Jdly, 1903. 



the " London Catalogue of British Plants " numbers 2'Si 

 species — thoxigh it must at once be pointed out that 

 this total includes no less than 104 " species " of that per- 

 plexina; irmius. Hieracium (HawkweedJ ; if we wish to 

 institute comparisons, this 104 species must be reduced to 

 say ten to twenty leading forms. Even with such a 

 reduction, the British Composite are still sufficiently 

 numerous, and offer a wide diversity of plant-forms ; but 

 certain limitations may be noted with regard to them. 

 Firstly, all are herbaceous ; among the many British 

 species neither tree nor shrub is found. And secondly, 

 despite the great variety of habitat which they effect, all 

 are terrestrial forms; some few may be found in wet 

 marshes, but none are aquatic. For the rest, they occur in 

 all situations, from salt marshes on the coast to the tops 

 of the highest mountains, and they assume all forms, from 

 tiuy annuals to great perennials like the Butter-bur, with 

 leaves which may attain six feet in height. 



We have already referred to the three sections into 

 which our species may conveniently be divided, exempli- 

 fied respectively by the Daisy, Thistle, and Dandelion. 

 Let us now glance more particularly into the native 

 species which fall under each of these groups, and note 

 their more prominent features. The Daisy group, or 

 Cortjmhiferie. includes not only all the Daisy-like flowers, 

 with a disk or centre of close-set perfect blossoms, and a 

 ray or margin of flowers with a corolla prolonged iuto a 

 conspicuous flattened limb, often of a different colour to 

 that of the disk-flowers ; but also a number of species 

 without the showy ray, such as Butter-bur (Petasites), the 

 pretty Cudweed group (Antennaria, Gnaphalium, and 

 Fila^o), the Mugworts (Artemisia), Tansy {Tanacetum), 

 Sea Cudweed {Blotis), and Bur-Marigold {Bidens). But 

 the presence or absence of ray-flowers is not an important 

 or even a constant character. For instance, some of the 

 Senecios have a ray, others none. Of these, the rayed 

 Common Ragweed (S. Jacohgea) and the rayless Groundsel 

 {S. vulgaris) will stand for examples ; yet the Eagweed 

 often is devoid of a ray, especially on coast sand-hills, 

 where the rayless form is often the prevailing one, and the 

 Groundsel may often be found with ray-flowers well 

 developed. The Common Bur-Marigold (Bidens cernua), 

 normally rayless, sometimes produces a ring of yeUow ray- 

 florets, which makes of this somewhat dull flower a quite 

 showy plant. Of stem forms, our Corijmbiferm offer no 

 great variety, the stems being usually herbaceous, upright, 

 and branched. The genera Petasites and Ttissilago 

 (Butter-bur and Colt's-foot), however, offer good examples 

 of strong uudergi-ound creeping stems. These are 

 possessed of much vitality, which makes the Colt's-foot a 

 very difficult weed to eradicate. Similarly, the Winter 

 Heliotrope (Petasites fragrans), a plant introduced from 

 Sicily for the sake of its fragrant flowers produced in mid- 

 wiuter, which has now run all over the country. From its 

 interlacing, far-creeping tangle of subterranean stems, a 

 growth of kidney-shaped leaves is produced, so dense as to 

 exterminate every native herb which it encounters. The 

 Flea-bane (Pttliearia di/senterica) and Saeezewort{Achilliea 

 Ptarmica) have likewise far-creeping underground stems. 

 The leaves of the Daisy group offer much variety. 

 Especially noticeable is the development of grey felt in 

 those species whose habitat renders it necessary to avoid 

 too great transpiration. The most remarkable example of 

 this is the rare Sea Cudweed (Diotis maritima), a plant of 

 drv gravel-beaches, the stems, leaves, and even involucres 

 of which are clothed with dense white felt, giving the 

 plant a most remarkable appearance. We may note the 

 same development of felt in the Cudweeds, all plants of 

 dry places. The Sea Wormwood has its home habitat in 

 salt marshes, and consequently fijids it necessary to 



economise water ; it also has its fine-cut leaves and its 

 stems and inflorescence uniformly covered with grey felt. 

 The Golden Sami)hire (Inula crithmoides), which has its 

 habitat on sea rocks, has developed exceedingly fleshy 

 leaves, like many of the halophytes, 

 or salt dwellers; like the Samphire, 

 after which it is called, these juicy 

 leaves are deliciously aromatic. It 

 is ])erhaps among some of the larger 

 members of the Daisy group that 

 the composite inflorescence attains 

 its greatest beauty and perfection. 

 Examine such a flower-form as the 

 Ox-eye Daisy. First we have the 

 close-lapping scales of the involucre, 

 securely enclosing the whole, and 

 protecting it when in bud. Then 

 the splendid ring of ray-flowers, 

 whose object is to render the in- 

 florescence more conspicuous. Thus 

 we find these enormously-expanded 

 corollas often assuming a tint other 

 than that of the main mass of 

 flowers — white, when the disk is 

 yellow, as in the Ox-eye ; in other 

 species blue, or purple, or yellow, 

 accompanying a yellow or greyish 

 disk. Tbese ray -florets have sacri- 

 ficed their perfection as flowers for 

 the purposes of advertisement, and 

 are usually devoid of stamens, or 

 sometimes devoid of both stamens 

 and pistil. Finally we have the 

 dense massof disk-florets, allperfect, 

 producing a quantity of minute 

 fruits. As for the fruit of the Coryin- 

 hiferae, a large number rely on wind 

 carriage, and the calyx-segments 

 take the form of hairs, which grow 

 into a more or less perfect parachute to aid in transporting 

 the comparatively large fruit to pastures new. These 

 parachute-fruits we know well in the Groundsel, Colt's- 

 foot, Hemp. Agrimony, and Sea Aster. A large numlier 

 of other genera, among them the Daisy, Ox-eye, Chamo- 

 mile, Mugwort and Yarrow, are devoid of conspicuous 

 fruit-appendages of this 

 kind, and apparently secure 

 bv the swaying of their 

 stems a seed-dispersal 

 sufficient for their needs. 

 The Bur-Marigold derives 

 its name from the fact that 

 its fruits are provided with 

 spines (the altered calyx 

 limb) armed with retiexed 

 hooks ; when ripe the fruits 

 easily attach themselves to 

 the coat of any passing 

 animal, and secure wide 

 dispersal thereby. 



Turning now to the Thistle group or C'ijnarocephile(e. 

 Here we meet with perhaps the handsomest of our Com- 

 positw — the Thistles, which must rank among the most 

 beautiful of all the plant-forms which our country yields. 

 Here, too, belong the Knapweeds (Gentanrea), and the 

 Burdocks (Arctium). In this section the flowers are all 

 tubular, as in the disk of the Corymbiferie. The flowers 

 are also usually longer, producing a more oblong head, and 

 the involucre-leaves (phyllaries) are more conspicuous in 

 form and colour than in the Daisy group. The Thistles 



Via. 2.— The Golden 

 Samphire. (Half natural 

 size.) 



Fia. 3. — Fruits of Bur-Marigold. 

 a, Bidens cernna ; h, S. trip srtita. 



