Étapes initiales du développement in situ de Claytonia caroliniana var. caroliniana

The early development of Claytonia caroliniana was studied in situ from seeds sown in wirenetting boxes buried in a maple stand near Quebec City. Seed germination begins in late October, more than 4 months after dissemination, reaches a level of about 50% at the end of December, and resumes in springtime. In April–May, one or two secondary roots appear on the most developed seedlings while the single cotyledon (C. caroliniana is a monocotyledonate dicot) shows up above the litter. Concurrently, the corm begins its development at the base of the primary root. A few days later, when the cotyledonary structure disappears, the corm enlarges slightly, new roots begin to form, and an apical bud is activated to initiate the first leaf. The first leaf can reach a length of 4 cm before the winter and will survive under the litter. In April of the following season, 2 years after the beginning of the cycle, the first leaf emerges from the litter, the corm diameter reaching no more than 2–3 mm at this time. The critical stage for the survival of the seedling comes at the beginning of its first summer, as it must produce a corm able to initiate a leaf. This is probably related to the precocity of seed germination. The early phenology of C. caroliniana as a whole resembles that of its adult stages. It differs slightly, however, from the development of C. virginica. Key words: Claytonia caroliniana, seed, germination, seedling, juvenile development.