The small tropical greenhouse, better known as the "orchid greenhouse", is in front of the Alpine garden. This warm, damp, shady micro-environment hosts a collection of tropical forest plants, including many epiphytes, plants which have adapted to living on the highest tree branches to receive more sunlight. Many of these forest species are still unknown to science, due to their inaccessibility and invisibility. Among epiphytes are several orchids: some are hybrids with large, gaudy flowers; others are spontaneous species with sometimes tiny flowers, but nevertheless coveted by collectors; still others are now rare and endangered in their natural habitats. An interesting orchid is vanilla (Vanilla planifolia Andrews), with fragrant flowers (containing vanillin). Here, artificial insemination is the only means of obtaining the fruit of vanilla, as pollinating insects (pronuba) are missing. Other curious epiphytes are tillandsia (Tillandsia sp. pl.), Bromeliaceae native to American tropical and subtropical regions, and platycerium (Platycerium sp. pl.), also called staghorn ferns because of the repeated forked shape of their leaves. The same greenhouse also contains several ferns, a few of which are tree-like, as well as a coffee plant (Coffea arabica L.) and tamarind (Tamarindus indica L.).