That spring came early this year seems like an understatement. Bulbs were coming up in February and many were flowering well before the first day of spring. And then came the backlash. Through the last week of March the temperatures dropped below freezing, even during the day. The flowers of the saucer magnolias, for example, shriveled and browned immediately.

The Chionodoxa flowers were entirely unaffected. The name translates as “glory-of-the-snow” and they are native to the high altitudes of eastern Mediterranean islands and adjacent Turkey. Chionodoxa is hardy to Zone 3 in the United States and Canada, where it flowers from late February through March.

The flowers are usually a sky blue to violet in color with a white center. The blooms are held upright on 4 to 6 inch stems that emerge from rosettes of long, narrow deep green leaves. The plants grow from bulbs that must go through an annual period of freezing temperatures. Once the bulbs are established, they begin to spread laterally by bulbets. It is not unusually to see large drifts of these little blue flowers extending away form a border back into an adjacent woodland. They are tolerant of partial shade and flower well before most deciduous trees leaf out.

A person more expert in her bulbs than I made me aware of the existence of Chionodoxa. I had never distinguished it from the Scilla, to which it is closely related. The tepals of Chionodoxa are joined at the base, while those of Scilla species are free. The flowers of Scilla sibirica and its varieties, which is encountered often in the northeastern United States, also hang downward. Most Scilla species, however, have blooms that are held upright like those of Chionodoxa.

Chionodoxa and Scilla species are so similar that many taxonomists do not even think that they should be in separate genera and would like include all the Chionodoxa in the genus Scilla. While the Chionodoxa has relatively restricted geographical range, is confined to alpine areas, and has only six wild species, Scilla taxa are distributed over much of Europe, western and central Asia, and northern Africa in many types of habitat.

The genus Scilla (and with it the much smaller and somewhat doubtful Chionodoxa genus) was once classified as a member of the lily family (Liliaceae), then was moved to the Hyacinthaceae in the 1990s based on analysis of DNA in chloroplast plastids, and most recently has placed placed under the Aspargaceace by some workers who have added analysis of more genetic material.

Regardless of their phylogeny both genera are popular among gardeners. Chionodoxa siehei or C. forbesii is the most commonly seen species. “Or” because there isn’t agreement as to whether they are one or two species. If they are one, then C. forbesii takes precedence (forbesii is described as having fewer flowers that are blue instead of violet). This variety is often incorrectly labeled C. luciliae, a different species. And to make matters even more confusing C. gigantea is an older name for luciliae that is still in use by some horticulturalists. C. luciliae/gigantae has only two or three flowers per stem, while C. siehei has 10 or 12.

The most commonly encountered Scilla is the Siberian squill (S. sibirica), which in spite of its name is native to the Caucaucus, not Siberia. It grows readily throughout the northern United States and regarded as an invasive pest in some place (e.g. Minnesota, Illinois) where it has naturalized in woodlands.

There do not seem to be a large number of cultivars of either Chionodoxa or Scilla sibirica, but ‘alba’ (white) varieties of both are common, and C. luciliae/gigantae is available in pink (‘Pink Giant’). The wild type of S. sibirica (also spelled siberica in some places) is a deeper, more saturated blue than Chiondoxa species, but it is also available in an even deeper blue variety called ‘Spring Beauty.’