36 Plant-life of the Oxford District 



more equal terms with the vestigial tree-types of underwood, as a dense mat 

 of growth at the forest-base, occupying all available substratum, and taking 

 the chances of light-supply and water-supply, to ultimately form associations 

 with the larger growths. Though it is evident that they would do still 

 better in more favourable stations, if the competing and dominant trees were 



removed. 



Enduring a wider range of vicissitudes of biological environment, such 

 herbaceous perennials come into further relation with the associated inten- 

 sive insect-life of similar seasonal activity; hence the flowers are predomi- 

 nantly insect-pollinated, while the seeds are more admirably fitted to with- 

 stand the rigours of the perennation-period, commonly materialized as 

 extreme desiccation of extra-forest region, and so tend to acquire a degree 

 of vitality far beyond that of the older woodland tree especially those of 

 damp forest which are not required to dry off at all, and commonly possess 

 little vitality when once dried (Oak, Walnut, Aesculus, Salix}. 



Such types constitute the bulk of the Flora of the North Temperate 

 extra-forest zone, and are largely represented in indigenous flora by many 

 genera and species, especially of such families as Cruciferae, Caryophyll- 

 aceae, Ranunculaceae, Leguminosae, Umbelliferae, Labiatae, Scrophulari- 

 aceae. Compositae, Gramineae, Cyperaceae, as representative families of 

 Herbaceous attainment. Locally some 500 plants come under this heading 

 in the wild flora, as well as a great range of forms in field and garden- 

 cultivation, as the most familiar flowers of arable land and pasture, hedges 

 and woodland clearings, where vicissitudes of the environment are at a maxi- 

 mum, and the working-period may be favourable for but 2-3 months in the 

 year. 



Annual Plants and Ephemerals. All the considerations drawn from 

 the case of the Herbaceous Perennial apply with increased force to the special, 

 case of the herbaceous monocarpic plant which presents the limiting 

 specialization as response to seasonal effects in the production of the ' mono- 

 carpic' habit, with one flowering and fruiting period in the life of the 

 individual. The soma does not perennate after once fruiting, but dies of 

 exhaustion in abundant seed-production, with no residual shoots to carry on 

 growth in a subsequent season. The seed-stage, that is to say, remains all- 

 sufficing for effective perennation, as the seed-stage may be specialized to 

 withstand the greatest range and duration of desiccation, heat, and cold. 

 This, however, implies the necessity of open ground for germination, and 

 the annual is of little value in occupied woodland or a closed formation, 

 save in clearings or on the death of larger organisms involving subjacent 

 vegetation in their decay. Beyond the forest-zone annuals stand a good 

 chance in the immediate occupation of ground in which normal perennials 

 cannot even perennate, whether from extreme drought or extreme cold. In 

 such cases early maturity and rapid seed-production alone gives tjiem 

 superiority over the herbaceous perennial ; as the latter in turn went one 

 better than the woodland tree. Such monocarpic plants are so far the most 

 highly organized representatives of the plant-kingdom, running parallel 

 with the extreme development of the insect-life of the land, in exact response 

 to the same seasonal range of the yearly period. The annual plant, again, 

 becomes the type so commonly exploited by man, as giving a crop, which 

 may be sown, harvested and cleared, with the provision of unoccupied 

 ground for its successor, in minimum time. 1 



Variations on the theme occur, as : 



(i) The Ephemeral, for which an even shorter period of optimum con- 



1 Cf. ' Ten Week Stocks' of garden cultivation, and a local race of Barley formerly harvested 

 9-10 weeks from sowing (Plot, 1705, p. 155). 



