chap. xii. polygala v ce;e. 355 



that he found this species in dry sandy barrens in New Jersey, and that 

 he is much inclined to think it is only a variety of H. ericoides: they 

 were both seen in abundance together; and many subvarieties were ob- 

 served, which seemed to unite the two. This curious shrub covers large 

 tracts of the dry white sandy plains of New Jersey, in large round tufts, 

 where it resembles very much the common ling (Call una vulgaris) of Scot- 

 land." Were all botanists, who, like Mr. M'Nab, are at once scientific 

 observers and practical cultivators, to exercise their common sense, as he 

 has done in this instance, we are persuaded that the number of alleged species, 

 in every genus which now contains a great many, would soon be con- 

 siderably reduced. The flowers of this kind of hudsonia are small and 

 yellow, and appear from May to July. Like H. Nuttalh*, this is somewhat 

 difficult of culture, requiring a peat soil, a shady situation, and protection 

 by glass or by snow during winter. All the species are readily increased 

 by layers, or by cuttings of the ripened wood, planted in sand under a hand- 

 glass. 



App. I. Other Species of Cistdcca?. 



Long as is the list of Cistaceae, and especially of helianthemums, in this 

 chapter, it might have been increased by the addition of various other species, 

 or sorts, described by botanists. The utility, however, of such additions is 

 very questionable. We have confined ourselves, as much as possible, to sorts 

 that are, or were lately, in existence in the neighbourhood of London ; and 

 for this information we have taken as our guide the Cistinece of Sweet, com- 

 menced in 1825, and completed, in one volume, in January, 1830. We think 

 we may safely assert that several of the sorts described in that work are now 

 no longer in existence; because, in consequence of their tenderness, and 

 liability to be neglected, they are continually dying off during winter, and 

 as continually being replaced by others raised from seeds, either imported or 

 saved in this country. The chief use which we propose to ourselves, in giving 

 so long a descriptive list, is, to show the numerous and beautiful forms assumed 

 by this family of plants, in order to promote their more extensive cultivation. 

 Supposing a cultivator about to form a collection of C'istaceae, we should 

 attach much less importance to his being able to procure all the sorts described 

 by Mr. Sweet, than to his obtaining all the sorts easily procurable, whatever 

 names they might pass under, and cross-fecundating them, so as to produce 

 new forms. There can be no doubt whatever that the sorts of both the genera 

 Cistus and Helianthemum might, by cross-fecundation, be increased ad in- 

 finitum; and, considering their very great beauty as border and rockwork 

 shrubs, we think they merit the attention of cultivators at least as much as 

 many florist's flowers. 



CHAP. XII. 



I 

 Lj 



OF THE HARDY AND HALF-HARDY LIGNEOUS PLANTS OF THE ORDER 



POLYGALA^CEiE. 



There is only one perfectly hardy ligneous plant belonging to this order, and it is of such humble 

 growth, that, for all practical purposes, it may be considered as a herbaceous plant, rather than as a 

 shrub. We have introduced the order, however, chiefly for the purpose of recommending gardeners 

 to try some of the beautiful Cape species of Pol^gala against conservative walls. 



C c 3 



