This past Thursday, we tried a new program at Ohio State University’s Secrest Arboretum in Wooster, new for us, yet ageless in importance: "How Plants Mate."
I have been interested since undergraduate days when, as a history major trying to rid myself of science requirements, I took basic botany at Ohio State University.
On the first day or so, I was confronted with just how ignorant I was: "Flowers become fruits," said Dr. Arthur H. Blickle.
Though surely this was taught to me from elementary school on, somehow it had not registered with any clarity. You mean if peach blossoms are killed by frost there will be no peaches? Duh.
Well, with such revelations, I soon changed my major to botany.
And I learned some important lessons about knowledge and teaching to others. We are all ignorant of almost everything — but not everything; we can build our knowledge base.
You don’t know something until you know it. And remember what it was like not to know. This last is important: I do remember what it was like, and do not scoff when someone asks why there are no peaches on their tree, even though they know they were killed by frost (not this year, thankfully).
So let us set up the basics we discussed in the class.
The Floral Envelopes. Since the flower is so key, the “leaves modified for reproduction in the Angiosperms (the flowering plants)” consider the four main components of a “complete” flower:
1. The calyx, typically made up of green leaf-like sepals.
2. The corolla made up of the often showy and colorful petals.
3. The androecium, the male part of the flower featuring stamens with anthers that contain pollen grains.
4. The gynoecium made up of the pistil(s) composed of an ovary at the base, a stalk called a style, and its receptive stigma at the tip which catches pollen grains from the anthers.
It should be noted there are many variations of this, but if all four of these floral envelopes (calyx, corolla, androecium, and gynoecium) are present, the flower is termed "complete." Having both male and female parts makes a flower "perfect" as designated by the Victorians, who provided many of these terms.
Pollination. To get from the gynoecium to the androecium, is an accomplishment of great wonder. Sometimes it is via the wind (anemophily) as is true for most grasses, oaks and walnuts.
Often pollination involves the highly successful co-evolutionary partnerships with insects and flowering plants (entomophily) involving bees and butterflies and other insects, with birds such as hummingbirds (ornithophily), bats (chiropterophily), and so on.
But there is more to it than just pollen reaching the stigma. Horticulturists must be aware of these conditions. For example, the timing must be right, and therein lies a story.
This leads us to more terms, namely monoecious and dioecious flowering habit.
Monoecious plants have male and female flower parts on the same plant, but in separate male and female blossoms. Dioecious, referring to “two houses” means that male and female flowers are on two separate plants.
Winterberry hollies are dioecious. So buy female winterberries, such as "Winter Red" and a male or two.
But which male? If you buy a "Winter Red" female, not just any male will do. It better be a male that produces pollen in synchrony with the ripeness of the stigma that is going to receive the pollen. As it turns out, a good choice is "Southern Gentleman." If you have "Red Sprite" synchrony, it is achieved with "Jim Dandy." A lovely story.
Pawpaws require two separate clones in order for them to overcome their "self-incompatibility;" otherwise flowers but no fruit, like in my backyard. I must get another clone!
Sweet cherries require at least two trees to produce fruit (love is sweet), sour cherries do not.
Complicated? Sure, but this is the fun of the culture of plants: horticulture. This is the essence of a green thumb.
Now let us turn back to something more ethereal.
The Pollen Tube. One of the wonderful hidden realities of flowering plants is the pollen tube.
Microscopic in size, you will not see it with the naked eye, but here is what happens. A microscopic pollen grain from the male anthers of a flower makes it to the female pistils, by wind, birds and the bees, bats or butterflies.
One nucleus of this pollen grain develops a tube nucleus that then delivers two sperm nuclei, each with one set of chromosomes from the male part of the flower. One sperm nucleus joins with an unfertilized egg, fertilizing it to form a zygote, that with more divisions, becomes a seed, The second sperm nucleus fertilizes a triploid cell in the ovule, forming the endosperm tissue that then nourishes the seed. The ovary ripens around the seed and endosperm, becoming the fruit.
Thus a tomato, and a green bean are, botanically fruits.
So a tomato is a fruit botanically, but … now, what is a strawberry?
First, it is ambrosia from heaven that is now about to arrive for us — are not berries the most amazing of all natural delights?
Yes, but let us pause: A strawberry looks all the world like a big juicy flavor-packed fruit with a bunch of seeds on the outside. But does that not fly in the face of the idea that a fruit is an ovary that ripens around the seeds inside, the very definition of the flowering plants, the Angiosperms, as compared to the other seed plants, the Gymnosperms with their naked seeds?
As we discussed this past week, this is not the exception that proves the rule. The juicy portion of the strawberry plant that we eat is actually the very tip (receptacle) of the tip of the flower/fruit stalk (peduncle) of strawberries.
What looks like seeds are fruits speckled onto the receptacle, with a seed inside each fruit. Strawberries are known as aggregate fruits because each flower has multiple ovaries, thus resulting in multiple fruits on that juicy receptacle.
Does that mean if I eat a strawberry I am getting dozens of fruits with each chomp? Yes, but it still takes eight large strawberries for one serving of fruit. Lots of vitamin C and potassium, and under 50 calories.
This is only the tip of the peduncle of what we discussed this week. Ann Chanon of OSU Extension in Lorain County regaled us with the intricacies of magnolia, buckeye and redbud flowers.
Jason Veil, curator of Secrest Arboretum, explained flower structure using our Secrest microscopic screenshots.
I talked about the pseudo-copulation of orchids. Say what? Yes, such a phenomenon exists, and Darwin even devoted a book about these and other fascinating variations of orchid sex.
Some species of orchids are pollinated by certain bees and wasp species that, over eons, have co-evolved with the orchids such that pollination, and the variability of offspring that occurs with cross-fertilization, is facilitated for these orchids. The orchids now mimic the females of the bees and wasps, the bees try to mate, and in doing so pick up a packet of pollen from the orchid and in attempting to mate with another orchid, voila — plant mating is initiated.
We did touch on mating in other types of plants, mosses, ferns and others, but seed plants, and especially the flowering plants (the Angiosperms) predominated … for it is angiosperms that have true flowers and true fruits that surround the seed with its embryo of an entire new plant and their nourishing endosperm.
Why so much on the flowering plants instead of the ferns and their allies and mosses and their mates? Because they are so cool.
As Goethe, a botanist and poet, said of the flower, the leaf modified for reproduction in the Angiosperms: La fleur est une feuille faite avec amour. I always thought this was translated as: The flower is a leaf mad with love, but at least one Googling indicated the true quote is: The flower is a leaf made with love. Without investigating further, I’ll take either.
Finally, let us remember that plant mating is about relationships, of the androecium and the gynoecium, of one plant to another, of one of a species interacting with another of a species, and of the relationship of species to other species.
With that, if a species is a group of related genera, what is next? The answer is that a plant family is a group of related genera. You can see it for yourselves: the bean-like pod of redbud (the genus Cercis) tells you that it is in the Fabaceae (the bean family).
The open flower with many stamens of Kerria at least suggests its relationship to raspberries (Rubus), apples (Malus), and Rosa, all genera in the Rosaceae. And the four petals and two pair of tall stamens across from each other and two single shorter stamens across from each other in Dame’s rocket (Hesperis matronalis) tell you it is a member of the mustard family, a crucifer, in the Brassicaceae and not a five-petaled phlox in the Polemoniaceae) with no such cross-like stamen array.
Come on now, have you not misidentified the white and pink and purple flowers along the roadside as phlox until now?
Does this whet your appetite? Up next in this particular series: on July 2 — "Plant Families III" then "Plant Parts Exposed" in the fall. Up next overall in the OSU Extension Secrest series is "Annuals and Perennials with Pam Bennett and Matt Shultzman" on June 27.
And for the ultimate in relationships:(Wo)Man’s relationship within nature, a nature neither to be conquered or feared, but one we are part of: mark it down: "Alexander von Humboldt: The Sestercentennial at Secrest" on Saturday, Sept. 14.
One final note: Now that we are talking history, as in the 250th anniversary of the great protoecologist, explorer, naturalist, geologist, mountaineer, and influencer of almost every scientist and thinker of the 19th century (I never would have sailed on The Beagle if not for Alexander von Humboldt — Charles Darwin), let us return to Arthur H. Blickle and that beginning botany class.
I see now that my mind was making connections, since only two weeks ago we had a program in Leetonia: "From the Carboniferous, to the Coke Ovens to Climate Change." At that program, we traveled back 358-299 million years ago to the age of tree ferns and high levels of photosynthesizing cyanobacteria and high oxygen levels, to the age when dragonflies had 3-foot wing spans.
Wait … how… could dragonflies be so much bigger then? Because insects have no lungs, only spiracles to let in life-needed oxygen. Their size is limited by oxygen concentration in the atmosphere. With more oxygen even their "inefficient" oxygen-acquiring physiology allowed them to fashion larger bodies.
At any rate, all those tree ferns and lycopods and protogymnosperms were eventually submerged and under pressure for long, long periods, turned into coal, petroleum, and natural gas. Fossil fuels today.
The coal was burned at those coke ovens of the 19th century in Leetonia with the coke used to fuel steel plants, and there are still over 200 remnant hobbit holes still in the sides of the hill there, where these Cherry Valley Coke Ovens are found in the Leetonia Beehive Coke Ovens Park. Then, as Springsteenesque "smokestacks rising like the arms of God" they "built the cannonballs that helped the Union win the War," there in Youngstown, there in Leetonia, and other parts of Ohio heritage.
Jobs and steel and climate change. Nothing is simple.
And here is Northeast Ohio (Springsteen again), now in 2-0-1-9, I check the internet, for Dr. Arthur H. Blickle, Ph.D. from the University of Cincinnati, and a career as professor at Ohio University, there he is: Psaronius magnificus n. comb., a Marattialean Fern from the Upper Pennsylvanian of North America. Gar W. Rothwell and Arthur H. Blickle, Journal of Paleoentology, Vol. 56, No.2: 459-468. The Upper Pennsylvanian, mid-Carboniferous, say 325 million years ago.
Speaking of ferns, we also will have a “Ferns, and Mosses, and Lichens, Oh My” class at Secrest later this summer.
So much to learn.
Jim Chatfield is a horticultural educator with Ohio State University Extension. If you have questions about caring for your garden, write to firstname.lastname@example.org or call 330-466-0270. Please include your phone number if you write.