One of the toughest and ugliest plants in our glasshouse is a night blooming cereus (Hylocereus undatus - probably). It grows up the aluminum struts and occupies the space at the top ends, some of the hottest and coldest, wettest and driest places there. No one ever tends it hardly, and then every now and again it will issue forth a set of flowers, often all at once. The flower buds are almost 12" long (30 cm) and about 2" (5 cm) in diameter. The perianth parts are numerous and spirally arranged starting out green at the bottom of the bud and shifting to white of the innermost parts. The fully open corolla can span 8-9". Within the light green to cream colored corolla are hundreds of stamens and a large mop-like stigma (quite obvious in the image above). This position allows it to pick up incoming pollen before the floral visit gets a new dousing with pollen. These flowers open at night because they are bat pollinated, and bats must be really good, really reliable pollinators for a plant to invest so much in a short-lived flower. One pollination event can result in hundreds of seeds. At any rate few people ever get to see the show because of the nocturnal flowering. And of course our glasshouse lacks blossom bats. This image is courtesy of Harvey McDaniel, Wikimedia Creative Commons.