Carpobrutus acinacif flower hottentot fig pink sour fig alien beach Carpobrotus edulis coast dune ecology flora flowers habitat ice plant introduction invasive natural nature plant sand soft Spain summer wild Aizoaceae angular-pigface Cape-fig carpobrotus-glaucescens coastal creeping-succulent daisy-like-flowers drought-resistant dune-stabilizer edible fire-resistant fleshy food groundcover Hottentot-plant ice-plant medicinal nutritional open perennials pigface pink-purple plant-mat prostrate salt-substitute salt-tolerant sand-dunes sand-stabilizer smooth-leaves sour-fig strand-ivy succulent sunlight sunshine thick triangular-leaves yellow bee bees insect insects