September, 1903,] 



KNOWLEDGE 



196 



style, occupying the axis of the bell, terminates in a stigma 

 lying right in the opening. Surrounding this, and a little 

 shorter than the style, are the stamens. The anthers are 



—b 



Fio. 3. — Diagrammatic Section of Flower of Erica Tetralix. 

 a, Calyx ; A, corolla ; c, filament ; d, anther ; e, style ; _/", stigma ; 

 g, ovary. Enlarged, 



roundish, and instead of splitting open, open by a pore at 

 what, in the inverted position of the flower, is the lower 

 end. Attached to each anther are two curious spreading 

 horns. The stigma and the horned anthers almost block 

 the entrance of the flower. Honey is secreted at the 

 further end, near the ovary. The flowers are visited 

 chiefly by bumble-ljees. The bee, alighting on the bell, 

 pushes its forehead against the stigma. At the same time 

 its proboscis, pushed into the flower in search of honey, 

 comes in contact with the spreading appendages of the 

 anthers, and the disturbance causes pollen to drop out 

 through the pore on the bee's forehead. Thus cross- 

 fertilisation is effected. As to the leaves. That the 

 leaves of many of these plants are curled backwards is a 

 matter of common observation, but it is only on careful 

 examination that we find how far this is carried in some of 

 the species. While in the little Azalea (Fig. 4, 1) the leaf 



fiQ. t.— Outline sections of rolled leaves of Ericaceie. 1, Azalea; 

 2, Andromeda. Enlarged. 



is mort'lv curved backwards, in others the curling is carried 

 so far that a chamber is formed, the edges of the leaf 

 almost meeting behind. The lower drawing on Fig. t, 

 which re]iresents a foreign species of Andromeda, ex- 



emplifies this peculiarity. Similar chambered leaves are 

 found in many plants— notably in grasses — and the object 

 they serve is to prevent too rapid transpiration ; the 

 stomata, which are situated on the back of the leaves, 

 being thus enclosed in a cool moist chamter. It may 

 naturally excite surprise that the Heaths, which are in so 

 large measure bog plants, growing in a soil reeking with 

 water, should be thus protected from loss of water. The 

 answer to this puzzle lies in. a peculiar property of boggy 

 soil, to which 1 have made reference in a previous article 

 (Knowledge, September, 1902, p. 210). The water- 

 logged soil is so badly aerated that soluble humus 

 compounds remain in solution. Plants find difliculty in 

 absorbing water charged with these substances, and hence 

 they take precautions against undue waste of water. Such 

 precautions we see in the small size of the leaves of the 

 Heaths, and their rolled character. 



To proceed with our review of the native 'Ericacese. The 

 British Vacciniese comprise only the genus Vaccinium, 

 which has four species. The familiar Whortleberry or 

 Bilberry (V. Myrtillus) needs no description. Note the 

 pretty pink urn-shaped flowers, produced almost before 

 the leaves, and the curious spurs on the anthers — very 

 characteristic of the Heath family. V. uliginoswn, the 

 Great Bilberry or Bog Whortleberry, is a small shrub with 

 the general appearance of the last, found on mountains in 

 Scotland and the North of England. V. Vitis-Idiea, the 

 Cowberry or Red Whortleberry, has its home amid alpine 

 rocks. It is a small shrub with creeping stems, producing 

 upright shoots which bear shinmg evergreen leaves like 

 those of Box, and pink flowers in which the corolla is more 

 deeply cleft than in the beforo-menti(med species, being 

 bell-shaped and five-pointed. The berries are red when 

 ripe. The last species, the Cranberry (F. nxyeoccus), is 

 one of the most delightful of British plants — a tiny shrub, 

 creeping among Sphagnum or short Heather, with long 

 thread-like shoots, and short, flowering stems which bear 

 exquisite pink blossoms with four recurved petals. The 

 leaves are recurved, glossy green above, white below ; the 

 berries large and red in colour. Altogether it is one of 

 the daintiest plants which has a ]:>lace in our flora. 



The remaining Encacex are plants of a quite different 

 appearance from any of the preceding. The Pyroleie are 

 represented by four species of Pyrola and one of Moneses. 

 The Pyrolas are pretty plants with a rosette of roundish 

 root-leaves from which springs an upright stem bearing a 

 graceful raceme of white or piukish waxy flowers, with 

 incurved petals and a remarkably long style. P. rotitudi- 

 folia is a rare plant of bushy and reedy places ; its flowers 

 have a peculiar appearance owing to the drooping style, 

 which protrudes from among the buntUe of stamens. P. 

 media and P. minor are of more frequent occurrence, in 

 heathy places. They have a tolerably close resemblance, 

 but may be distinguished by their straight style, which is 

 much longer than the stamens and crowned wth a ring in 

 P. media, ('(lual to the stamens and without a ring in 

 P. minor. The fourth s(>ecies, P. secunda. is montane in 

 habitat, and distinguished, as its name implies, by the 

 flowers on the raceme all facing in one direction (secuud). 

 The leaves, too, are oval, pointed, and serrate ; instead of 

 more or less orbiculiu- and slightly crenate, as in the other 

 species. The style is long and straight, with a large 

 stigma. Mor.es'es grandiflora is a rare north-Scottish 

 wood plant, allied to Pyrola, but with large single whit« 

 blossoms. 



Lastly we have the Monotropeee, represented in our 

 country" bv the single species Monotrnpa Hypopitys — or 

 Hypop'ifys' Monotropa, if one prefers that. This curious 

 fliiwer has none of the characters which we associate with 

 the Heath family. It is a pale yellowish plant, devoid of 



