Traits de vie comparés de deux espèces du genre Syzygium (Myrtaceae): l'une exotique envahissante à La Réunion, l'autre indigène

Abstract

The fruits and seeds of Syzygium jambos (L.) Alston and S. cymosum (Lam.) DC. var. cymosum, the seedling emergence in a nursery and the seedlings of three months old are studied in the aim to identify which traits differ between the former species, invasive alien in La Réunion island, and the last, native of the island. These two species are alike in certain respects: fleshy fruit, seed water content at ripeness (about 50% of the fresh weight), hypogeal germination and leaf area of the seedlings coming from a fruit. But S. jambos and S. cymosum greatly differ according to the following attributes: the natural scattering unit, which is respectively the seed and the fruit; the viability rate of the seeds after one week of drying, which sets up respectively at 92% and 13%; the seedling emergence velocity since 70% of the seedlings emerge respectively for each species in 25 and 50 days; and the photosynthesis which starts earlier among S. jambos seedlings. These differences contribute to explain the invasive potential of S. jambos and are consistent with results of other studies.