Inside The New York Botanical Garden

A Botanist is Never Bored!

Posted in Learning Experiences on March 14 2013, by Scott Mori

Scott A. Mori, Ph.D., Nathaniel Lord Britton Curator of Botany has been studying New World rain forests for The New York Botanical Garden for nearly 35 years. He has witnessed an unrelenting reduction in the extent of the forests he studies and, as a result, is dedicated to preserving the diversity of plants and animals found there.

The wilted flowers of the four o'clock plant at 11 a.m.
The wilted flowers of the four o’clock plant at 11 a.m.

At the time of this writing, I am in São Paulo Brazil to attend a multinational meeting of scientists, each participating in a study of the plants and animals of the Amazon Basin. I arrived the day before the meeting, and had time to walk through the area around the hotel, exploring for weeds and cultivated plants. No matter where I travel, even in the largest cities, there are plants to enjoy. When I spot one I know, it is like running into an old friend and trying to remember his or her name.

First, I try to identify the family the plant belongs to, followed by the genus, and finally the species. After recalling its name, I study the plant to find out if there is something about it I have not seen before. The secret to discovering new information about a plant is to study it carefully through a hand lens–I prefer one that magnifies the flower, fruit, and seed parts by up to ten times their normal size. Finding a plant that I do not know provides an even more exciting encounter, but that will be left for another post.

Immediately after I left the hotel at 11 a.m., I spotted a four o’clock plant, scientifically known as Mirabilis jalapa (Nyctaginaceae family) and commonly cultivated in North America. At the time, the previous day’s flowers were wilted and drooping downward, but many others were in bud on the plant. Fast forward to 4 p.m. when passing the plant a second time, I noticed that the day’s flowers were open, the petals were fully expanded, and both the filaments and style formed beautiful coils placed within the calyx tube; two hours later, on my way to eat dinner, I passed the plant once more and discovered that the filaments and style were fully expanded. I also noted the stigma protruding a short distance beyond the anthers.

Open flowers at 4 p.m.
Open flowers at 4 p.m.
Mirabilis jalapa
Even though the flowers are open, the stamens and stigma are still coiled in the flower.
Close-up of the coiled stamens and style.
Close-up of the coiled stamens and style.

When the anthers and the stigma are placed at different levels, it forces the pollinator to make contact with the receptive anterior side of the stigma before it touches the anthers. The process increases the chances that pollen on an approaching pollinator will be deposited on the receptive side of the stigma. In contrast, pollen placed on the pollinator while in the flower is not rubbed off on the receptive part of the stigma when it exits the flower. This insures that pollen from the same flower is not deposited on the stigma of the flower, thereby increasing the chances of cross-pollination.

Although I did not come back later in the evening to look for pollinators, it is known that Mirabilis jalapa is pollinated by hawk moths. Most moth-pollinated plants flower after sunset, offer pleasant-smelling nectar, possess a narrow corolla tube, and have lightly-colored calyx lobes. All of these features characterize hawk moth-pollinated plants. It has been demonstrated that colder weather makes hawk moths inactive and results in self-pollinated flowers. In contrast, hawk moths are more active on warmer nights, resulting in more flowers being cross-pollinated. Once I knew this plant’s name, I was able to search for information about it on the internet. Knowing the name of the plant is, thus, the first step in finding out more information about it!

A fully open flower at 6 p.m. with the stigma and stamens protruding from within.
A fully open flower at 6 p.m. with the stigma and stamens protruding from within.

There is still so much to understand about plants that I learn something novel with every walk I take in a new city. Whether exploring the world of plants for enjoyment or as an aspect of scientific study, botanizing includes identifying plants, understanding how flowers are pollinated and seeds dispersed. I find the best way to remember what you learn is to take pictures of more than just the habit of the plant, because many common plants have had their portraits taken many times. On the other hand, relatively few close-up images have been snapped of the fine details of flowers, fruits, and seeds–even in the case of the most common plants.


Sharon Romero said:

This is fascinating! Thanks for sharing the story and photos.

Dave Wood said:

Isn’t this called Belle de Nuit (Beauty of the Night)?

Scott A. Mori said:

Hi Sharon,

I saw many interesting plants on my trip to São Paulo and will be discussing them and many other spectacular plants in future posts.

Scott Mori

Rhizowen said:

I have grown Mirabilis jalapa, a lovely plant. My main interest in the genus Mirabilis is in M. expansa, the Andean root crop known as mauka. This has much smaller flowers than M. jalapa and no discernible scent. I have managed to produce seed crops from it, although it I would love to learn more about how it is pollinated in its native range.

Scott A. Mori said:

Hi Dave,

Yes, it is also called the belle de nuit because it is in full flower during the night. It is also called the 4 o’clock plant because the current day’s flowers open around 4:00 pm.


Scott A. Mori said:

Hi Rhizowen,

Thanks for tell us about Mirabilis expansa. It was great to learn about the edible tubers it produces. The flowers are nocturnal and have a long tube indicating that they are also pollinated by hawk moths.


Scott A. Mori said:

Dear Readers,

I made a mistake in my discussion of Mirabilis jalapa (see my labels on the images). The petals have been lost and it is the sepals that have fused to form what looks like a corolla tube but is really a sepal tube.


Dan Nickrent said:

Scott – I hate to come across as a “quibbler”, but do you really stand by your last statement “On the other hand, relatively few close-up images have been snapped of the fine details of flowers, fruits, and seeds–even in the case of the most common plants.” Have a look at PhytoImages and We now have over 100,000 images on the two sites combined, and many of these are close-up, macro type photographs. In general I agree with you, that most botanical photos are not good macro shots showing diagnostic features of the plant. Our efforts to assemble a digital flora of the Philippines ( depends upon taking good quality macro photos. Currently PhytoImages has over 15,000 images from that country. And we welcome photo contributions from anyone!

Scott A. Mori said:

Hi Dan,

When I say details of flowers, I do not mean just taking pictures with a macro lens. In order to understand what makes a species belong to a plant family or learn the characters that separate species, the flowers and fruits often need to be dissected. Digital photography allows that information to be made available to the world.I have learned the utility of digital images for understanding the floral and fruit structure of my main research interest, the classification and ecology of the Brazil nut family. Close-ups of flowers are useful but what is really helpful are medial longitudinal sections of the male part of the flower. I have written an essay about how to photograph species of the Brazil nut family (see

The images on the Philippine website are wonderful!