Stigma Stigma: Misadventure in Identifying Plants

Hundreds and perhaps thousands of unidentified plant photos lurk in my hard drive. I’ve always intended to manage and catalogue them, maybe make blogging an excuse to learn the botany world one species at a time. I daresay I’ve failed and should try harder.

One of my earliest photos back in March 2012 includes this deceptive blue-purple, raveled flower. Are there enough features to use a dichotomous key or refer to by a proper photo in a field guide? I suspected it might. Colours can change from the wrinkly, pre-bloom stage to the outstretched stage, but surely the three-forked stigma was one of those kinds of traits unique to a particular family?

Mystery Stigma

My great mystery. Inside the flower all you can see is the three-way split of the pistil. Outside you can see the colour, the leaf shape, the bulge of the ovary, and hints at the number of petals and sepals (base of petals).

Excited about using a dichotomous key for the first time in years, I opened Keys to the Flora of Arkansas by Edwin B. Smith, and began.

General question: Monocot or dicot? I shall guess dicot. Most are.

1: Parasitic or not parasitic? Not. Parasites tend to be rooted into another plant and many don’t have pigment because they’re busy borrowing nutrients to do anything for themselves.

3 (because parasites have #2): Cactus-like or not cactus-like? I dare say not cactus-like.

4: Chlorophyll or no chlorophyll? The green speaks for itself.

6: Aquatic or terrestrial? I remember it on land. Just a vague memory. I walked to it.

7: Woody at base or not? Not. See Key E.

1: Sunflower or dandelion like? Nope.

2:Flowers imperfect, arranged in a cup-shaped cyathium with 1-5 glands on the rim of the cup ( the glands may bear petal-like appendages); plants with milky juice.” I…have some glossary checking to do, but all the while, at least I know it’s not the answer, Euphorbia (milkweeds).

3: Are flowers “papilionaceous”? I remember that word being popular in my taxonomy class. The TA and some of the chattier classmates thought it should be our catchphrase. I looked up the term, but I know it’s not the answer, Leguminosae aka Fabaceae (pea family).

4: Vine? No. Next question.

13: Stamens evident? Well, the petals are closed, but I have guess and play the odds and go with yes.

14: Flowers perfect or imperfect? I actually remember what this means. Again, I assume there are both male and female parts–perfect–and take the next step of this dangerous guessing game.

15: Here’s where I went wrong: Perianth? I assumed that referred to the ring of petals, as though the word “corolla” didn’t exist.

My assumptions led me to the wrong sub-key and I quickly got lost and simply checked photos of the plant families to see what looked structurally similar. When I got frustrated I tried my field guide, Wildflowers of Arkansas by Carl G. Hunter.

Primroses and petunias, judging by small photos, mostly closely resembled my photo but none of them had the main clue I had: the three-forked stigma.

I checked online using DiscoverLife. Again, I got a lot of similar “looking” flowers, but none just right. I checked the scientific names in an image search: petunias often had forked stigmas. But they weren’t three-pronged.

Google searches didn’t find it. Neither general keywords nor “three forked linear leaf flower” and variations. Wild petunias didn’t have the narrow leaves. Mexican petunias lived at least two hardiness zones away and at the other end of the state.

Mature flower diagram.svg

Obviously I didn’t consult such diagrams and figured my rusty botany knowledge would suffice.

By Mariana Ruiz LadyofHats – Own work, Public Domain, Link

I revisited the dichotomous key. I realized my error with “perianth” and that it doesn’t refer to the ring of petals but also the ring of sepals embracing the petals’ base. All right, now I can check the right sub-key, not Key E-2 but…

16: Flowers regular or irregular? Petals seem even in relation to each other. Probably regular.

17: Ovary inferior or superior? Well, at least I recalled this one correctly, and my photo distinctly shows the bulging ovary above the sepals. Superior.

18: Pistil or Pistils? The three prongs definitely stem from one.

19: Many or 10 and fewer fertile stamens? I speculate 10 or fewer because I know which key uses petunias and that’s my best lead.

20: Corolla partially tubular? That’s what my photo says–there’s fusion halfway to the base.

Go to Key E-7.

Once again the lack of a naked flower to look at plagued me and I couldn’t answer the rest of the key. I checked against other photos. Clearly this is one of those days that I’m making things harder than they should be, and there’s a simple answer?

Study Tools of Botany

The tools of the trade when you don’t have a physical specimen: internet, book with dichotomous key, book with field photography, and book with all the academic knowledge.

Plant families have a particular set of traits. I have the book: Vascular Plant Taxonomy by Zack E. Murrell. I should had started here considering my hunch.

I flipped through the pages, glanced at all the families’ introduction pages complete with illustrations and quick descriptions, and what pattern do I see? Not only do the descriptions not mention pronged stigmas, but many mention multiple or lobed styles.

Oh, I see how wrong I led my day. Of course it was the styles that were split, not the stigmas! And of course the trait is common. Clearly I was vaguely recalling that some other lobed trait was unique and indicative of a specific family.

What is this flower? I don’t know. This is a sit-at-home, armchair misadventure in science.



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