Seed germination of two critically endangered plantain species, Plantago algarbiensis and P. almogravensis (Plantaginaceae)

The aims of this study were to determine the seed size and the effects of temperature and light on germination of Plantago algarbiensis and P. almogravensis seeds, two endemic species from Portugal that are at risk of extinction. The temperatures tested were a constant 15 or 25°C and an alternating temperature regime of 25/15°C, combined with 16 / 8 h light / dark photoperiod (light) or constant darkness. The results showed that P. algarbiensis and P. almogravensis have non-dormant seeds. Although P. algarbiensis seeds are larger and heavier, seeds of both species have similar germination requirements. The best germination results were obtained at 15°C under either light or darkness, along with the shortest mean germination time. The results are crucial for developing conservation strategies for these Plantago species.