192 



HINTS AND NOTES 



nating with more open conditions. But every- 

 where it is never so protected or sheltered as 

 in a true woodland. 



In the first case the heath is exposed to the 

 full glare of the sun. The flowers that bloom 

 in the open association are not usually large 

 and conspicuous, but they are frequently sweet- 

 scented, e.g. Furze and Broom, and Ling, 

 Heather, Hawkweed, Sheep's-bit Scabious, 

 and Harebell are also attractive to insects. The 

 masses of Ling and Heath, Broom or Furze 

 together form a conspicuous feature; hence by 

 association they attain the same end that indi- 

 vidually conspicuous flowers do in the matter 

 of attracting insects. On a small scale the 

 Blue Milk Wort, Starry White Grassy Stitch- 

 wort, Pretty St. John's Wort, Tormentil, Heath 

 Bedstraw, Eyebright, Red Rattle, Cow-wheat, 

 are also attractive. 



In the case of the tree types and the Spike 

 Rushes, Sedges, and Grasses, as a rule the 

 flowers are proterogynous, the stigma is 

 feathery, and the plants are pollinated by aid 

 of the wind. The flowers of the Creeping 

 Willow are also resorted to by bees. Thus 

 the vegetation of the heath is adapted equally 

 to cross-pollination by insects and to wind 

 pollination, its open character being advan- 

 tageous in both respects. 



The Dispersal of Seed of Heath Plants. 

 Undoubtedly wind plays a great part generally 

 in the dispersal of the seeds ef ericetal plants, 

 on account presumably of the extensiveness of 

 the dominant types, and of the need for dis- 

 persal to a distance. Thus Ling, Heath, 

 Milkwort, Cat's Foot, Hawkweed, Sheep's-bit 

 Scabious, Harebell, Red Rattle, Cow-wheat, 

 Creeping Willow, in addition to the Spike 

 Rushes, Sedges, and Grasses, have their small 

 seeds scattered by the agency of the wind. 



Two plants have an interesting mode of 

 dispersal, viz. Furze and Broom. The elaio- 

 somes afford an attraction to ants, which carry 

 them away, and feed upon the nutritive matter 

 they contain. The seeds are also dispersed by 

 an elastic movement, the crackling of the gorse 

 being a well-known feature in spring and early 

 summer. Some of the heath plants rely on 

 other animals for dispersal, as Heath Bed- 

 straw, the fruit bearing hooks ; Whortleberry, 

 the fruit being edible and eaten by birds. 



The Soil. There is one feature of heath 

 vegetation which makes it more uniform than 

 most formations; this is the nature of the soil, 

 which is always of the same character. The 

 plants that grow upon heaths are thus unable 

 to grow elsewhere, and attempts to transplant 

 them without a considerable thickness of the 

 soil, as the gardener well knows, are usually 



fruitless. This is largely due to the association 

 of a mycorhiza or fungal mycelium with the 

 roots of the plants, especially in the case of 

 the Heath proper. 



Peat is an organic soil derived from the 

 remains of plants which accumulate and form 

 a thick deposit above the subsoil. It differs 

 from the mild humus found in woods which 

 is neutral or alkaline, and well aerated and 

 dry in being acid or deficient in lime, more or 

 less damp, and poorly ventilated. The passage 

 from humus to peat is largely regulated by the 

 water-content, or state of humidity, and the 

 depth of the deposit. In the last stage a heath 

 passes into a moor. 



The soil upon which this organic deposit is 

 formed is usually sandy or gravelly, or of a 

 similar nature. Moorpan is formed by the 

 cementing of gravel by humous acids, and 

 where this is the case trees will not grow. 

 The type of soil of a common or grass heath 

 is usually sandy, and there is at most a very 

 thin layer of humus. 



Method of Survey. A heath presents a 

 more or less uniform type of formation. There 

 is no zonation, save at the periphery of a 

 region of wood (or scrub), and except where 

 it is wooded it presents a series of dominant 

 associations or societies, which can be studied 

 on a broad basis, and mapped as in the case 

 of moors and bogs. Apart from the lines 

 formed by the extent of the Ling, Heaths, 

 Furze, Broom, W'hortleberry, &c., there are 

 the lesser societies that endeavour in more 

 open spots to maintain an existence. These 

 should be carefully studied, as in the case of 

 meadows and pastures, by staking out squares, 

 and the plants counted, or put down on squared 

 paper. The dominant plants in these cases 

 should be noted, and their percentage esti- 

 mated. 



Where there is woodland, this should be 

 studied as in the case of woods (Section IV). 

 The influence of the tree growth on the heath 

 types should be noted, as also the form of the 

 wood or the alternation of wood and heath. 



The openness and extensiveness of a heath 

 makes it especially adapted to the study of the 

 plants from the ecological point of view; for 

 there are no barriers, and a base line for the 

 squares to be studied can be laid down almost 

 anywhere. 



The particular conditions of soil, the effect 

 of light, wind, &c., should all be studied in 

 relation to the adaptations of the plants to 

 meet the special conditions in each case. 

 Advanced students may make pot cultures, 

 make observations on the rainfall or light in- 

 tensity, water-content, &c. 



