Which four ecological specializations occur among species in the heath family?

Within the heath family (Ericaceae), there are four distinct and largely mutually exclusive lines of ecological specialization:1

• Xeromorphic leaves: Approximately 1,300 species have evolved these leaves, which are adapted for environments with limited water or nutrient availability.1
• Fleshy fruits: About 1,500 species produce fleshy fruits, which are primarily dispersed by birds and sometimes mammals.1
• Pollen with viscin threads: Roughly 900 species utilize these fine structures to hold pollen tetrads in clumps, facilitating pollination by insects, birds, or bats.1
• Epiphytic or epilithic habit: About 400 species are specialized to grow on other plants (epiphytes) or on rocks (epilithic).1