Our summers are too hot and dry for primroses. Near the sea-shore the air is cool and moist enough, but we shall never have primroses by the million in our woodlands, and we have no conception of dozens of alpine species which English amateurs tuck away in rock and bog gardens. One of the finest mass effects I saw was a colony of Primula Japonic a, about one hundred plants, forming a ground cover under azaleas. It is hardy in our Northern states, but I doubt if it would self-sow as it does in England. Many of the primroses have piercing crimson and purple tones, and Primula Japonica seems to me enjoyable only in deep shade.
Musk is another plant which the English can grow by the hundred or thousand as a ground cover in bog gardens or beds of rhododendrons and azaleas. It is a dear old plant, but there are much finer things for use on a large scale. We need not weep because we cannot grow it well in quantity.
Gunnera, pampas grass and flame flower (or torch lily) are the only other plants of the first importance in English bog gardens that are not hardy in our Northern states.
On the other hand, it is highly probable that we shall be able to develop an American type of bog garden which will be very charming for we have a finer set of orchids and insectivorous plants, and we have many finer species of the heath family, or Ericaceae.*
* For studies of swamp societies see Coulter's "Plants," pages 183 to 192 and the Fifteenth Report of the Missouri Botanical Garden, pages 38 to 71. "A New Gardening Hobby for Americans" in Garden Magazine for July 1007, pages 342 to 34s describes six types of bog garden. For "The Cultivation of Hardy Orchids," see Garden Magazine for August 1906, pages 12 to 15. See also works mentioned at end of Chapter VIII.