Friday Fabulous Flower - night blooming cereus

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.

Friday Fabulous Flower - a screwpine

Although most tropical plants are day neutral, and although most of the plants in our glasshouse are tropical, an great deal of flowering occurs now as the days begin to get longer again.  Here's and interesting, and in our glasshouse, unreliable flowerer, a member of the screwpine family (Pandanaceae), Freycinetia multiflora.  As can be seen the stem and foliage give this scrambling shrubby vine a bamboo-y sort of appearance, and it can climb by means of adventitious roots to the tropical forest canopy.  This one actually isn't in flower yet, but the flowers are tiny and borne on three club-shaped inflorescences hiding (for now) underneath the inner whorl of orange-sherbet colored bracts, which are the attractive part. The smaller image shows one of the inflorescences emerging; these are dioecious plants, and this one bears staminate flowers.  According to the literature, pollination is basically vertebrate, nectar/pollen feeding bats and birds, although possums may also effect pollination. On the whole is has a rather unusual look to it, but then again, all screwpines have a strange sort of look to them.

Plants that acoustically interact with bats

Nectar-feeding bats are great pollinators, but locating flowers at night can be difficult. While not having the high pitched, highly tuned sonar of insectivorous bats, nectar feeding bats get some help from plants that have parabolic reflectors that bounce their acoustic signals right back at them as they approach flowers. While several flowers, like the standard petals of these neotropical legumes (Mucuna), have acoustic reflectors, new research has found a plant that grows leaves with a parabolic shape right above their inflorescences to guide bats to their flowers.

Jade vine - Another ludicrous flower to enjoy

The jade vine (Strongylodon macrobotrys) is a tropical liana (woody vine) from the Philippines. If you know your plant families, you’ll recognize these flowers as beans/legumes right away (1 standard petal, two lateral petals, and two petals forming a keel housing the stamens and pistil) except what a color! This pale blue-green color is very unusual flower color, but it shows up well in dim light against a dark and green background, which abounds in the rain forest understory where the Phactor works.

Each individual flower is about 2 inches long. And like wisteria, which the Phactor is told flowers, his own vine providing no evidence of this at all, the inflorescence hangs upside down, so each flower twists 180 degrees on its stalk to present itself right side up. Some tropical fruits have a similar pale blue color, again to show up well against a dark background, and the Phactor promises to show you one soon.

The inflorescence of flowers is a foot or two long and hangs down from the vine on long cord-like stems. And this combined with the color tells me that the pollinator is a nectar foraging bat! A similar bean (Mucuna holtonii) grows in the neotropics, but the flower color is just a pale greenish, however the upper petal of this bean’s flower acts as a sound reflector to bounce the bat’s sonic signals back at them (research conducted by Dagmar and Otto von Helversen; you meet the best people while doing field research.). Jade vine is now fairly common in conservatory collections at botanical gardens, like the New York Botanical Garden which is where this picture was taken (eat your heart out GrrlScientist).

The flowers work by lever action. The weight of the bat pushes the keel down forcing either the pollen laden anthers or the stigma out the tip of the keel to make contact with the bat’s body. Unfortunately never having seen bats and the jade vine in action, I don’t know how exactly the two interact, and very unfortunately, the native habitat of both are threatened by deforestation. It’s depressing to know that someday such organisms may only live in cultivation. At least this Asian import won’t escape into the wilds of the Bronx.