Confusing PLANTS / Taxonomy Misconceptions

I :heart: this thread:

Confusing animals/Taxonomy Misconceptions

Where the author (Harrison Elkins) wrote:

However, plants did NOT get any love in the 111 replies!

I’m currently next to a patch of lavender, which is a mint. I’ve looked it up before, but I forgot that it was a mint!

Which plant taxonomy do you keep forgetting, or getting confused by?


Today I learned lavender was a mint!!


Mint family has square stems.

But there is (of course!) a Pelargonium that hasn’t read the rule book


“Is this a plant or a weed?” – Fairly common question. Confusing for a botanist because of course weeds are plants.

That’s not a weed; it has pretty flowers! – Some weeds do have pretty flowers. Sigh.

Grasses don’t have flowers – Of course grasses have flowers. They’re just reduced and hard to see.

Everything with long narrow leaves is a grass. – Maybe, but maybe not. Sedges and rushes also have long, narrow leaves and inconspicuous leaves. A long list of plants, some of them dicots, are called “grass.”

Every white-flowered member of Apiaceae (the Carrot Family) should be feared as Poison Hemlock (Conium maculatum). Sigh. Most Apiaceae are not Poison Hemlock and Poison Hemlock itself won’t reach out and poison you. Just don’t eat it. And no, your toddler isn’t likely to stuff his mouth with this – it smells (and presumably tastes) bad.

“Leaflets three, let it be.” – Well, OK, it’s a good first rule if you’re clueless about plants because Toxicodendron (Poison Ivy, Poison Oak) causes such a bad rash. However, many other plants, including strawberries (Fragaria), many raspberries & relatives (Rubus), and Box Elder (a maple, Acer negundo) have three leaflets. They’re harmless.

This has oak leaves – it must be Poison Oak. – No, if it has undivided (but lobed) leaves, it’s an oak (Quercus). Poison Oak (Toxicodendron diversilobum) is a different species in an entirely different family.

Hay Fever is caused by Goldenrods (Solidago). – No, Goldenrods put up conspicuous yellow flowers to attract bees at the same season that Ragweeds (Ambrosia), Kochia (now Bassia scoparia), and many other late-season, wind-pollinated species release their pollen in the air.

Roses cause rose fever, a spring version of hay fever. – No, but they bloom at the same time as many wind-pollinated trees that have inconspicuous flowers and release their pollen in the air.


I have a few questions:
What’s a dicot?
What determines if something is a ‘grass’ as opposed to a sedge/rush/whatever
If I see a cool “grass” that I wanna upload to iNat, how should I go about photographing it to make it as easy as possible to ID?

Monocots have flower parts in 3’s, usually leaves with parallel veins, scattered vascular bundles. Examples include lilies, onions, irises, arums, cattails, grasses, sedges, rushes, palms, and many many others. However, most plants are dicots. Dicots have flowers parts in 4’s or 5’s, mostly, leaves mostly with net-like arrangement of veins, and vascular bundles arranged in rings. Examples include roses, carrot, tomatoes, thistles, daisies, geraniums, cucumbers, most broad-leaved trees, beets, melons, and so many others.


(Adapted from Harrington, H. D., 1977. How to Identify Grasses and Grasslike Plants.)


Thank you!!

Not many people on iNaturalist photo enough parts of a graminoid (grass or grass-like plant) for us to identify it unless it’s easy. With graminoid we’d like to see the following photos:

Whole plant! Don’t forget this when taking the close-ups!

Base of plant, base of shoots. Often useful colors, hairs, structures there.

On the leaf, photo the area where the blade meets the leaf sheath (the part that wraps around the stem). We want to see any hairs, any flaps or collars, the ligule, and how open or closed the sheath appears to be. It’s a good idea to take one photo with the blade pulled a little bit away from the stem, so we can assess the ligule (a flap or line of hairs at the base of the blade).

Whole inflorescence (to show branching pattern). If your camera insists on focusing on the background, put your hand behind it. A close-up on the inflorescence is good, too.

Whole spikelet (basic inflorescence units, usually each on a stalk), or, in the rush family, the flower.

Then break the spikelet apart. Photo the pieces lying on your hand or something. If there are awns (bristles, hairs) include those. (In rushes, open the capsule and photo the dust-like seeds. Ideally, turn back some tepals – the brown petals – so we can see the stamens.)

You don’t always need all these photos, but if you don’t know what you have, you don’t know what you need.

What if you don’t have all these parts? Go ahead and post it. Some grasses can be identified from really bad or distant photos. Others I’d hate to try even with an excellent series of photos because I know those species are hard to ID even in the hand. Do I always take all these photos? No. And sometimes I wish I did. So it goes.

If you do photo all these parts, will it be identifiable? We wish. Sometimes. They improve your chances. But not always. Graminoids can be hard.


A botany professor had taught me a mnemonic for distinguishing graminoids that has stuck with me:
sedges have edges, rushes are round, and grasses have asses like you and I
(the last line refering to grasses usually being hollow, word choice is for ryhming reasons)

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Everybody agrees on the first two lines of that little saying, but there are lots of variants on the last one. There’s nothing for that last line that fits the rhythm and rhyme.

By in large, the first two lines work. Most sedges have triangular stems with the leaves therefore going out in 3 directions, though some have round, flattened, even square stems (but you’d never mistake Eleocharis quadrangulata for a mint). Most rushes have round stems but a few have flattened stems. Most grasses have round stems (a few flattened stems) with leaves going out in 2 directions.


Some misconceptions or terminological confusions I’ve encountered around plants:

  • “(All) plants have flowers and seeds”
  • “Mosses aren’t really plants”
  • “Liverworts aren’t plants, they’re a fungus”
  • “Mushrooms are a kind of plant”
  • “Clubmoss/spikemoss/firmoss are a kind of moss”
  • “Cycads are palm trees”
  • “Pine trees have flowers”
  • “Coral/anemones/etc are plants”

Plus, there is perennially a lot of confusion and mixed understanding around terms like tree, fruit, flower, etc.

There are also misconceptions about the dangers and health benefits of plants, most of which are specific enough that I don’t want to call them out in case I’m wrong, but sometimes they are very broad statements, like “invasive plants are probably poisonous but native plants are probably safe”.


I too get frustrated with people on Facebook wringing their hands over the dangers of a toxic plant that surely must be removed from their yard because it will kill their pet/child/livestock. Poisonous plants don’t reach out and poison you (except poison oak, but unless you inhale smoke from burning it, it won’t kill you, merely make you miserable). We mammals have co-evolved with plants and instinctively don’t eat enough to die from most of them (dosage matters) because they taste bitter or acrid or very sour, or they burn your mouth chemically (peppers) or with tiny needles (Jack-in-the-Pulpit, Dieffenbachia, and relatives). Oh, a few taste good, including Water Hemlock according to the few survivors, but it grows in marshes, not your front yard.

I also wonder, if you want to remove all the toxic plants in your yard will you remember to take out all the rhubarb, parsnips, potatoes, Prunus (cherries, plums, etc.), apples, oak trees, daffodils, squill, larkspurs, yew trees, etc., etc.?

Sorry. We do need to be careful about poisonous plants, but I’m on five or six Facebook pages about plants and after reading so much fluttery panic about toxic plants, I begin mentally snarling, “Well, if your toddler eats enough of this to die, maybe that will improve the gene pool!” Not that I really want that to happen, but . . . .


Ah, yes. Recently somebody on Facebook wrote that he didn’t want to use regular (unnatural) rat poison because it poisons animals that eat the rats and was thinking of spreading castor beans (Ricinus communis, source of ricin) around his yard instead because it is natural.

Sometimes you just want to weep.


Sometimes natural selection just isn’t working as fast as we’d like. (I’m only partly kidding.)


I am haunted by the FB plant from hell

I pruned mine last week. Still standing. Scrubbed the layer of latex off my hands, and secateurs. FB loves to hate that plant!

Try this plant
From across the path it is … a bulb with long narrow leaves.
But - it is a daisy - the clue is in the longitudinal veins on the leaves.

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That Corymbium glabrum is confusing! Looks like a grass and then when it flowers, just one flower per head? Or something like that?

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So far it doesn’t look like anyone addressed the actual question. Think back on your history of identifications – which ones have you gotten wrong multiple times?

  • It took me a while to learn how to tell lung lichens from thalloid liverworts.
  • Some Acanthaceae have flowers that look a lot like Lamiaceae. It doesn’t help that both families have opposite leaves. And then you bring in certain Plantaginaceae which also have flowers that look like Lamiaceae.
  • Some Cyclanthaceae look like seedling palms.
  • Most confusing of all to me are leafy succulents which turn out not to be Crassulaceae.

When you consider how many invasive plants were brought over specifically because they are edible, this one is a real howler.


Thanks for the tips!! I’ll try to keep this in mind in the future :))

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Yeah, my generation is proof of that :/