I have already made the remark in a former communication that the clear and bright atmosphere of this section of the United States seems particularly adapted for collections of this nature; for many delightful plants which luxuriate in the colder yet purer air which prevails in the higher regions of the Alps, will not bear the humid and foggy atmosphere of England; these are often introduced, but as often perish; here they would probably be permanent.
I may possibly have enlarged more on this subject than can be interesting here, where few of these artificial structures exist, yet as it is almost certain they will be shortly introduced, and if once introduced, are sure to become common, especially as the materials both for their erection and ornament are in plenty, I may be pardoned for endeavoring, while opportunity is mine, to create an interest in a pursuit which has afforded me so much pleasure.
I conclude with a list of some of the most showy and conspicuous plants for this purpose, beginning with those which are found in this immediate vicinity.
Houstonia Coerulea, and longifolia, bluish and long-leaved Houstonia. The former blossoms from middle of May to the middle of June in clusters so thick, that no stem can be seen, about three inches high, and may be gathered plentifully at Cambridge and Dedham, it is only annual; the long-leaved variety is perennial, an inch or two taller than the coerulea, but is a much rarer plant, I have only seen it near the granite quarry at Quincy, it was then in blossom in August.
Mitchella repens, the Checkerberry, this is almost too well known to require description, but its beautiful hairy white flowers which are extremely fragrant, and the bright scarlet fruit which succeeds them, would be greatly ornamental to rock work; it abounds every where.
I do not know that this beautiful plant grows any where in this immediate vicinity, but it covers the rocks at Gloucester, Cape Ann, Plymouth, and a variety of other places, it is held in the highest estimation in Europe, and well deserves it. The fruit is rarely seen, nor do I remember a description of it any where; it is about the size of a small wood strawberry, white, pulpy, with divisions like those of an orange, the interstices filled with beautiful small black seeds, the flavor of this pulp is of a most delicate sweetness, which only remains an instant on the tongue, and appears as if formed for the food only of an ethereal humming bird.
This is more ornamental in its red-berried fruit than in the flower - it is found every where in the neighborhood.
Dalibarda ripens and fragrarioides, the white and yellow Dalibarda, very lively little creeping plants, somewhat resembling the strawberry, but the flowers much more elegant from the delicacy of the stamens. Dr. Bigelow says they are found in woods in Princeton and in Hanover, N. H.; I have not been to these places, but found them plentifully creeping over rocks imbedded in moss in Maine, flowering there in August, here rather earlier. [Dalibardia fragarioides, is now called Waldstenia.]
Rue-leaved Anemone, and Anemone nemorosa - Wood Anemone. The first, which is from 8 to 12 inches high, is found in plenty at Dedham, the other everywhere in woods; they are white and very ornamental.
These are well known, and as they are early, are extremely desirable to satisfy the impatience of those amateurs who are constantly on the look-out for signs of the approach of their season of enjoyment. Many other plants of this description abound near Boston, but I must pass on to those of other climates.
The first are almost the whole tribe of Saxifrages, one of which, vernalis, though not sufficently showy for our purpose, is the earliest flower that blows near Boston. Saxifraga granulata, which may be purchased here, I recommend as most conspicuous.
The next are a tribe of thick-leaved plants called Sedums and Sempervivums or House-leek, amongst these the yellow stone-crop and the Sedum teratum, both ornamental, are well known here.
The family of Campanula afford a liberal subscription towards our design. C. pumila, white and blue, erinus and many others adorn the rocky places bordering the Mediterranean.
Several creeping Geraniums which blossom throughout the summer are appropriate plants. G. sanguineum, Lan-castriense and Wallichianum are to be had at the nurseries in this country.
Dianthus montanus, Mountain pink, with several others of this tribe, are extremely pretty.
Money Wort. This requires a damp soil to flourish, but must be kept in subjection, or it will overrun all the rest.
Lobelia bicolor and erinoides, with several others of this tribe, small bright blue flowers, very lively.
Tiarella cordifolia, a pretty plant with spikes of elegant small greenish white flowers, a native of the older woods in this State.
Fragaria Indica, or Chinese Strawberry. The bright red strawberry-like fruit of this is very ornamental to the rock in autumn.
CeraStium tomentosum, Mouse-eared Chickweed, has a small -white woolly beautiful leaf, and for this genus a large white flower.
I have given a list of enough for a beginner, and shall be happy to continue it if these structures at all increase.
There are many other plants, not referred to in this article, which will be found in the body of this work, under the heads of their respective genera, that are recommended for rock-work.