The five-second night-blooming orchid

Cryptobotany

Abstract

The “five-second night-blooming orchid” was first seen during the remarkable garden party of Mr. Wilson in Evanston, Illinois. It was the cherry on the cake of his incredible gardening practice because the orchid bloomed for only about five seconds after forty years of vegetative growth. We did not, however, know anything more about this species as Mr. Wilson refused to reveal the origin of the seed he planted. It took more than 25 years until another specimen of this orchid was found and later on, it was also found in the wild. The present overview summarizes the unique adaptation of this plant, called immature pollination and known only in it.

Taxonomical status of the orchid

Although several reports suggested that this particular plant is an Arum (family Araceae), these were mainly based on the extremely rare blooming and the shape of the flower bud. Some parallels were made with Amorphophallus titanium, which bloomed every 7 to 10 years and only a single flower emerges. The shape of the leaves, as well as the shape of the fully opened flower, however, suggests it is a true orchid, a representative of another monocot family, the Orchidaceae. Further study of the flower as seen during its blooming suggests it is a female flower. Thus the species is supposedly unisexual (bearing only male or female reproductive organs on the same flower) and further, dioecious (a single individual bears only male or female flowers). This is apparent from the carpel, seen during blooming, while no stamens are visible.

The origin of the plant remained largely unknown, but we could speculate it is a tropical species. Unlike many orchids, it is not an epiphyte but a free-growing plant. The vegetative growth is very slow, although the plant reached a substantial size. The single flower is also large, supported by a thick calyx. The sepals are unusual – yellow with red bands and offer a good defense of the developing flower. Currently, the Latin name, given by the scientific community is Nocturegina breviflores Wilsonii or short-blooming night queen.

Mechanism of blooming

The blooming of the night queen orchid is a truly spectacular event, which last sometimes less than five seconds. The flower development starts between 35 and 45 years of vegetative growth. Blooming occurs only at night and proceeds in all stages of the normal blooming but is fast-paced. The most spectacular sighting, however, is the rapid color change, from bright red to purple and finally yellow. This is caused by the abundance of anthocyanins and the rapid change of pH from acidic, when these compounds are red, to neutral, which caused them to turn purple to blue, and finally alkaline, which turns them yellow. This pH change is driven by compartmentalization of hydrogen cation and their partial movement from the petals to the ovarium, causing pH drop and hydrolyzation of the barrier, separating the female and male gametes. Thus, the blooming of the female flower is needed for fertilization rather than pollination like in ordinary plants.

Immature pollination – a unique mechanism

To understand this unique short blooming, we need first to take a look into the process of sexual reproduction in plants. This process is separated into three major phases – pollination, followed by germination of the pollen grain, and fertilization of the egg to produce seeds. We know for sure that Nocturegina breviflores does produce seeds, as the single plant is known to be planted from seed. What is also sure is that the extremely short blooming time is far from enough to allow pollination. Pollination does occur when the pollen grain is transferred to the stigma either by the wind or by an animal vector – bird, bat, or insect. The main function of the flower is to provide optimal conditions for this to occur. Animal vectors are often attracted by color, scent, food, and even shape like in many orchid flowers that mimic a female insect. Neither the blooming duration nor other characteristics of the “night queen” flower are beneficial for such a thing to occur. Another possibility, self-pollination within the closed flower bud was also denied as the flower we saw was female and lacked anthers.

Figure 1. The appearance of closed buds (A) and fully opened flowers (B). Before opening (C), the pollen grain (1) has already germinated, formed the pollen tube (2), and reached the embryo sac (3) with the egg cell (4). It has not penetrated because of the thick polysaccharide barrier (5). After flowering (D) the fast change in pH activates enzymes that hydrolyze the barrier (6) and allow the pollen to fertilize the egg cells.

It was not until the moment when pollination of this orchid was observed in the wild, in their homeland Madagascar, that cryptobiologists truly understood this unique process. It was called immature pollination as the pollen grains are transferred to the female flower bud in the very first stages of development. First, the male gametophytes (the male plants) do bloom much more often than females – actually every year after their 5th year of vegetative growth. They also bloom during the night and attract several species of the tiny mouse lemurs, sticking pollen grains to their whiskers. The newly formed female flower bud releases volatiles, very similar to female mouse lemur pheromones, thus attracting male lemurs. The flower bud is active for years, so thousands of pollen grains may be deposited on it until one of them is successfully enclosed by the bud.

This is the signal for the bud to start to develop. Then the pollen germinates and forms the pollen tube simultaneously with the development of the ovary. Then, both the egg and the sperm may stay dormant for years (Fig. 1). What breaks this dormancy is not known, but we should clearly state that the actual fertilization would not occur without blooming. This is because a very thick barrier of polysaccharides and proteins between the male and female gametes restricts fertilization. The rapid change in pH toward extremely acidic figures is needed for this barrier to be destroyed and fertilization to occur.

References

[1] Nick Castle. (1993) Dennis the Menace. Warner Bros. Pictures

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