Scilla is a large genus in the Hyacinthaceae family (or most recently in the subfamily Scilloideae under the umbrella of the Asparagaceae) with most species found in Europe, North Africa and western to central Africa. There are also species from tropical Africa, India, and South Africa. Some are winter growing and some are summer growing. Some prefer part shade that doesn't dry out in summer and others prefer sun with summer dry. Scilla was the topic of the week in December 2003. We were provided with an excellent Introduction by Jerry Flintoff.
All species grow from true bulbs that are either submerged under the soil or project above the surface. (See the Geophyte page). The flowers are usually blue (sometimes white or pink) with six anthers. Scilla sensu stricto has round filaments, anthers that are somewhat perpendicular to the filaments, usually blue pollen, and petals are distinct and independent to each other. Scilla sensu lato includes Chionodoxa, by as a separate clade or section: Scilla sect. Chionodoxa. The section (sometimes included as part of the "Scilla bifolia group") has different floral morphology than Scilla sensu stricto, but has been confirmed by molecular analysis as well as the ability for species of Scilla and Chionodoxa to hybridize.
It was proposed by a number of taxonomists to break this genus into many smaller genera, some with only a few species. For more information about the proposed changes consult Julian Slade's post. Many years later some of these changes, but not all, have been accepted.
The classification of the species of Scilla is difficult and variable, as there are many different things botanists and taxonomists have looked at to separate the genus into different clades or even into new genera. Older methods relied on floral morphology alone and resulted in many species being included in the genus. In the last fifty years the genus has repeatedly been restructured based on seed and seedling morphology, bulb characteristics, and most recently by genetic markers found in molecular studies or depictive protein crystals found in the bulbs.
Many members of the Hyacinthaceae (aka Scilloideae) were at one time included in the genus Scilla. Many taxa have been moved into different or new genera, or proposed genera such as (but not limited to):
The genus Chionodoxa is now widely considered to be included in Scilla, sometimes as a part of the Scilla bifolia group or as Scilla sect. Chionodoxa. Here is a simple Dichotomous key to help in differentiation between Chionodoxa, Puschkinia, and Scilla sensu stricto (Scilla in the strict sence).
Here are a few representative pictures of species that have been retained in the genus Scilla:
†Scilla in the broad sense. Due to some differing points of view and a relative state of confusion, this table includes some synonyms of species once included in Scilla.
‡Species with this mark have been moved to new genera. The links go to the new genera.