This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
The Snowflakes are almost as familiar as the Snowdrop. In this genus the segments of the perianth are almost or quite equal in length, and the anthers open by slits instead of pores. The name is from the Greek yeukos, white, and iov, a violet.
1. L. vernum. Spring Snowflake. - Flowers, as its name denotes, in Spring. Scape 1 or rarely 2-flowered.
2. L. cestivum (fig. 236). Summer Snowflake. - This species flowers in July. This and the foregoing both resemble the Snowdrop, but they are taller in stature; and this has several-flowered scapes. Both are natives of Europe.
Fig. 236. Leucoium aestivum. (1/4 nat. size.)