Euphorbia botany lesson

13 years ago

This is my attempt to explain why I love Euphorbias...not just because of their incredible diversity, their amazing growth forms, and (admittedly sometimes subtle) beauty, but also because I find them fascinating from a botanical point of view.

Probably old news to some, but if it's not, read on if you'd like! And there will be some pics, eventually :)

Even so, this post will be a little dry :)

The genus Euphorbia, with some 2000 species, is one of the largest plant genera. It encompasses everything from well-known species like Poinsettia and Crown of Thorns to little-known obscurities, and giant (30M) trees to little gems that never grow larger than a few inches.

This genus was first described by Linnaeus in 1753. Most other plant genera have been relentlessly re-described over the years, split and combined, and plants moved from one genus to another.

But Euphorbia still stands, more or less as originally described. Why? Because of cyathia.

A "cyathium" (plural "cyathia") is a flower structure that's unique to Euphorbias. No other plants have this.

The main part of a cyathium is the "involucre" or cup. So-called because it really is shaped like a cup. On the edges of the cup grow the "nectar glands." Yes, they produce nectar to attract pollinators!

What's more interesting is what grows from the inside of the involucre. Flowers!

But these aren't typical flowers with petals and everything you'd expect flowers to have. Instead, they're flowers that are reduced to their essences....the reduced female flowers in Euphorbias retain only what makes them female, namely, the pistil. And the male flowers, likewise, only have their male parts, namely, the stamens.

If you look at the bottom of this pic, you can see how the male and female flowers grow out of the involucre: {{gwi:559644}}

But Euphorbias have a few tricks up their sleeve. Sometimes cyathia only produce female or male flowers. Sometimes they produce both. Sometimes a single plant will produce both, but only on separate cyathia. Sometimes a plant will produce cyathia with only male or female flowers.

Time for a few pics!

E. godana. The nectar glands, growing from the involucre, are bright orange in this species. You can see a few female flowers (their stigmas always divided into three in Euphorbia) and many male flowers.

E. tortilis with lots of male flowers, sinking into the sap from the nectar glands:

{{gwi:559648}}

E. tortilis again, showing female flowers:

{{gwi:559650}}

Usually the nectar glands just produce a lot of nectar:

Sometimes they get a bit crazy, like in E. albipollinifera:

{{gwi:559654}}

As you can see from the diagram above, "cyathophylls" grow from the bottom of the involucre. Sometimes they're pretty:

{{gwi:559655}}

...and sometimes outstanding:

Thanks to Riki for permission to use the above diagram, and you can find out much better info here!

http://www.euphorbiaceae.org/pages/about_euphorbia.html

-R

Sort by:Oldest

Comments (16)

johnh_or
13 years ago
last modified: 9 years ago
Nice write-up and fantastic pics! I love this plant....
You might enjoy this site....Frank is the Euphorbia GOD!!!!

Here is a link that might be useful: EVERYTHING Euphorbia
0
beachplant
13 years ago
last modified: 9 years ago
Thanks for the lesson & pics. Euphorbias Rock!
Tally HO!
0
Related Discussions
'The Botany of Desire' on PBS tonight
Q
Comments (21)
Some good comments by everyone. Hman, while I agree with some of what you're saying in principle, I may differ on some of the specifics. Namely, I'm not certain Amish ground is all that more productive than those that farm conventionally. I know you live where there are a lot of Amish folk, and they have a reputation of being outstanding farmers, but I wonder if their reputation exceeds its worth. The reason I say that is that although I've no experience with the Amish, I do have experience with the Mennonites. They too, have a reputation as very good farmers. Indeed most have a strong work ethic. However, I used to examine their production records (pig farmers) and while, on average their production was above the mean, it was only slightly so. That improvement seemed to be dependent upon cheap labor (their large bunches of children). In the whole scope of things I'm not sure that agricultural model is the best for the planet (meaning the huge volume of people already on the planet). But like I say, I've little knowledge of the Amish, and even less of their specific farming practices. I will say that there are commercial corn growers getting over 300 bushel/acre, which is very productive indeed. One may think that kind of production is burning out the ground, but it doesn't appear to be so. I've seen some of that good corn ground in IL. It's been farmed for decades and decades, and still the richest looking black stuff you ever saw. I think part of the key is that the land was flat, so in the years where tillage farming was the rule, none of that good stuff was ever washed away. Probably the biggest threat to it is urban encroachment gobbling up that prime land. Keepitlow, Well said. However, I might take issue with the the part that our food quality has declined. This is pretty hard to discuss objectively though, because the word "quality" is so subjective. Additionally, it also depends on what years are being discussed. I'm just about through reading a different kind of American history book. It's the first book of it's kind that I've read. Most history books examine the "important" events of history (i.e. Revolutionary war, Civil war, etc.) and spend little time discussing the day to day lives of ordinary citizens. This book is the opposite. It's spends almost all of it's time discussing daily life, and ignores the "major" events. What I'm coming away with reading this book, is the profound struggle to survive before, and during the early part of the industrial age. This idea of southern plantations with abundance, defining the way of life was not the reality for the most folk. Before the modern industrial age the average American life span was amazingly low, largely due to inadequate and poor food quality. Even in somewhat later times, the food quality has seemed to improve. I remember hearing former U.S. Secretary of Agriculture Earl Butz speak. He gave examples of how food quality had increased since he was a kid (no worms in cereal, no worms in apples). I once read Upton Sinclair's book "The Jungle" about the meat packing industry in the early 1900s (actually I didn't finish it, it made me too sad. I may go back and finish it some day). Anyway, that book described conditions of meat packing as so bad, that reportedly Roosevelt was reading the book at his breakfast, and spit a mouthful of sausage across the table. From that book came the rigorous meat packing inspections we have today. This is getting a little long. Better stop here.
...See More
Euphorbias Dropping like Flies
Q
Comments (8)
Would not have expected to have a reason to reference my own "deadliest summer" thread, but this was the first summer wet enough to kill some Euphorbias in my garden since 2011. Didn't mention it there because for me, it's such an insignificant plant. They self-seed in the drier parts of my garden, and in fact, this spring, I killed off a whole bunch of them. Other than a couple that seemed to have an improved flowering head. In fact the heavy rains killed off the original plant from Joy Creek - got it in the first order I'd ever placed from them, back in 2006 or 2007. It was declining anyhow. Normally, however, they are quite tolerant to wet spells in my climate (coastal mid-Atlantic USA) - which is a pretty wet climate! Provided they have very well-drained soil and full sun to help 'dry off'. You must have REALLY over-watered them! Tsk tsk! They are almost native to your area, so can normally put up with a lot of summer dryness. As GG said. I wouldn't count them out btw. This is basically an elegant weed we're talking about. Some plants like Rhododendrons are more or less dead once root rot reaches an advanced stage, but yours might recover. They might look bad for the rest of the season, but put on healthy new growth next spring. Unlike a true shrub, a sub-shrub is regenerating stems throughout its life.
...See More
Senecio deflersii, and more botany :)
Q
Comments (3)
Yale, I'm sorry your plant didn't make it. It seems like for a lot of plants, there are different "clones" in cultivation, some easier to grow than others. I probably got lucky and have an easy-to-grow one. I tried to untangle the complicated taxonomy of this species, and here's what I found: it was described as S. deflersii by O. Schwartz in 1939, then moved to Kleinia deflersii by Halliday in 1984. Notonia obesa, described by Deflers in 1894 and moved to Kleinia obesa by Halliday in 1988, is now included in S. deflersii. Jacobsen (and others, I think) moved Kleinia and Notonia into Senecio in the 1970's, so O. Schwartz's description (as S. deflersii) takes precedence. I don't know enough about these plants to understand the difference between Kleinia and Senecio, and my interpretation of the taxonomical changes may be faulty -- it's just my best guess! -R
...See More
Visit to The Aloe Farm, hybridisation lessons
Q
Comments (6)
Woman, Rob ;) I am indeed lucky to be related. He also tissue-cultures aloe vera for supply to landscapers Hoovb it is some kind of peglerae. Whether a species or one of his cultivars, I'm not sure but by the look of the flower, it's probably been bred to look like that. South Africa and Southern California have very similar climates. It's all very brown at the moment because it is winter, it greens up considerably after the rains come. The person I was with bought Aloes, I have many already. I wanted small things to plant between the aloes
...See More
plant_junkie
13 years ago
last modified: 9 years ago
Wow that was really informative. Thank you for that post! I really enjoyed it. I have yet to become a fan of the Euphorbias because of their toxic sap. Not a big fan of allergic reactions :)

Steve
0
lzrddr
13 years ago
last modified: 9 years ago
The sap thing is way overstated, at least from my experience. I have over 200 Euphorbias and only when I go out of my way to hack off branches does the sap issue become an issue at all. To me it is sticky only... unless I get it in my eye. Never had much more of a reaction than that (save Euphorbia tirucalli which seems to be a tad more irritating)... never heard too many people make the same complaints about the sap in Plumeria circles, and is basically the exact same stuff... I did a lot more pruning when I had plumeria so the sap issue was a lot bigger deal for me then than now, now that I have pretty much killed off all my Plumeria. Lots of other plants have nasty saps (Jatrophas, Synadeniums, Oleandar, even some Aloes and cacti)- some irritating, as well as incredibly staining saps. My main issue with the saps is they gum up my pruners. But my blue cedar does that even more so.
0
land3499
Original Author
13 years ago
last modified: 9 years ago
Thanks all for the kind words!

johnh_or, Frank Vincentz's site is a great reference. But it hasn't been updated since 2006, nor does he post any more...I hope he's okay!

I'm with lzrddr, have never had an adverse reaction to Euphorbia sap, although I've never gotten it in my eye...that sounds painful!

Cheers,
-R
0
norma_2006
13 years ago
last modified: 9 years ago
That was a terrific lesson, Are you near So. Calif. travel time of no more then 40 minutes? If so do you give programs? My group is looking for speakers, of course you will be paid. Norma
0
wandering_willow
13 years ago
last modified: 9 years ago
I know this is an old post, but I just wanted to compliment and thank you! I love euphorbias, and was very curious about what united this expansive genus - you really explained it better than any other site or book I could find!

Thank you!
0
land3499
Original Author
13 years ago
last modified: 9 years ago
Thx WW, your kind words are very much appreciated.

GO Euphorbias! :)

-R
0
hanzrobo
13 years ago
last modified: 9 years ago
Awesome! Very informative! I have only a few of these. I have avoided euphorbias partly because of the sap, mostly because they're not as easy to cultivate as other succulents. Any tips on propagation would be appreciated. I will check out those sites listed above.
{{gwi:488792}}
0
blueskies12
13 years ago
last modified: 9 years ago
Excellent lesson!!! I am not all that interested in Euphorbias, but always love to learn, this was very informative. Reminds me that the last botany class I took did not even cover Cactaceae. :(
Thanks, Jenna
0
amccour
13 years ago
last modified: 9 years ago
"I have avoided euphorbias partly because of the sap, mostly because they're not as easy to cultivate as other succulents."

I've actually found Euphorbias to be a loooooot easier than cacti. This might sound weird but I feel like they give you better feedback when they're not happy, whereas cacti have a weird tendency to look fine up until they collapse.

Also having looked at this again I think the E. Nyassae I have is either a Godana or has some Godana DNA in it. Because while it looks more or less LIKE anE. Nyassae, it has the growing habit and flowers of a Godana. Except they're coming out of where they would as per a Nyassae.

I need to get pictures uploaded. That greenhouse had a lot of weird plants that I've never been able to properly identify.

"never heard too many people make the same complaints about the sap in Plumeria circles, and is basically the exact same stuff..."

Aren't Plumerias supposed to have worse sap, being closely related to Oleanders?
0
norma_2006
13 years ago
last modified: 9 years ago
First I want to thank you on the lesson you posted information that I didn't know, I didn't know that both the male and female parts can be on the same plant. I have to give some of my Plumeria plants away because I have allery problens. I kept only a few of this species. I find them easy to pollinate by hand. I have problems of gathering the seed. Norma
0
land3499
Original Author
13 years ago
last modified: 9 years ago
>I've actually found Euphorbias to be a loooooot easier than cacti.

For me, some (globulars/medusoids) are easy, but others (mostly the shrubby ones) are hard. The problem I have with the shrubby species is keeping them over the winter. I grow increasingly convinced that they need a lot of water, at least once every two weeks.

amccour, not sure about E. nyassae vs. E. godana. The editors of the Euphorbia Journal say that they've never seen E. nyassae in cultivation. In any case, it should be easy to tell apart from E. godana:

{{gwi:559079}}

This is E. nyassae in habitat (from The Euphorbia Journal):

{{gwi:559659}}

Norma, thanks for your kind comment.

Another way of looking at the Euphorbias is that they're either monoecious (from the Greek "one house"...meaning a single plant will produce cyathia with both male and female flowers) or dioecious ("two houses"...a single plant will produce either male or female flowers).

One more factoid :) The shrubby species are all monoecious, and don't hybridize. The globular species (for example, E. obesa) are all dioecious, and are tramps, hybridizing with anything they can find. :)

-R
0
amccour
13 years ago
last modified: 9 years ago
{{gwi:559661}}

It's this thing.
0
amccour
13 years ago
last modified: 9 years ago
Which in retrospect doesn't really look much like a Nyassae OR a Godana.
0
land3499
Original Author
13 years ago
last modified: 9 years ago
Agreed, it doesn't look like either.

To me, it looks like one from the E. schinzii complex, maybe E. uhligiana (although it doesn't seem to have a caudex) or something close to that.

Nice spine shields!

-R
0

Euphorbia botany lesson

Comments (16)

johnh_or

beachplant

Related Discussions

plant_junkie

lzrddr

land3499
Original Author

norma_2006

wandering_willow

land3499
Original Author

hanzrobo

blueskies12

amccour

norma_2006

land3499
Original Author

amccour

amccour

land3499
Original Author

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

Euphorbia botany lesson

Comments (16)

Related Discussions

land3499Original Author

land3499Original Author

land3499Original Author

land3499Original Author

COMPANY

BUSINESS SERVICES

GET HELP

CONNECT WITH US

land3499
Original Author

land3499
Original Author

land3499
Original Author

land3499
Original Author