HABITUAL AUTOGAMY IN LINARIA-TURSICA VALDES ET CABEZUDO (SCROPHULARIACEAE)

Reproductive biology of Linaria tursica (Scrophulariaceae), a small an nual species endemic to the coastal mobile sands of SW Spain was studi ed. Observations were made on flower and fruit development, pollen/ovu le ratio (P/O), breeding system and pre-emergent reproductive success (PERS). Flowering starts at the end of January or beginning of Februar y and continues till May, when the plant completes its vegetative cycl e. Flowers are autogamous: pollination takes place in the corolla tube , which is totally closed by the palate and by the two corolla lips, w hich spread after pollination is accomplished; fruit development immed iately follows pollination. Flowers take 3-4 days to develop and withe r; fruits take 9-14 days to grow and dehisce. Low P/Q ratio, high frui t/flower and seed/ovule ratio, and PERS values close to 1, both in con ditions of allogamy and autogamy, indicate that L. tursica is a strict ly autogamous species. This, together with a short life cycle, gives L . tursica a high capacity to adapt to the unstable habitats where it o ccurs.