Do Mammillaria have extrafloral nectaries?

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loyall
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Do Mammillaria have extrafloral nectaries?

Post by loyall »

Do Mammillaria species have extrafloral nectaries?
DaveW
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Re: Do Mammillaria have extrafloral nectaries?

Post by DaveW »

I can't find any reference to Mammillaria's, but Coryphantyha's which may be mistaken for Mammillarias often have. However they are increasingly being found in other genera too like some Opuntia's.

https://www.cactus-art.biz/schede/CORYP ... a_SB26.htm

https://opuntiads.com/oblog/extrafloral-nectaries/

Ferocactus of course have extrafloral nectaries.

https://tightloop.com/blog/2021/02/16/e ... fire-ants/
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MrXeric
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Re: Do Mammillaria have extrafloral nectaries?

Post by MrXeric »

I agree with Dave, a Mammillaria with extrafloral nectaries is most likely a Coryphantha :)
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loyall
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Re: Do Mammillaria have extrafloral nectaries?

Post by loyall »

The reason I asked about nectaries is that my M. microheliopsis has a few small brown goo spots on old flower bud scars in the axils between tubercles. I wondered if these could be nectaries. My plant is a windowsill plant so there are no ants. To be clear these scars represent flowers that did not pollinate and fruit, nor did they fall off. They were reabsorbed into the stem after blossoming.
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MrXeric
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Re: Do Mammillaria have extrafloral nectaries?

Post by MrXeric »

I've seen spent flowers leak nectar on Haworthia and Bulbine, but not on my cacti. Could be a humidity issue? Not sure. I would clean off the goo with a squirt of water on watering day. You can also use cotton swabs or a paint brush if you don't want to wet the entire plant.
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greenknight
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Re: Do Mammillaria have extrafloral nectaries?

Post by greenknight »

Maybe use peroxide to clean it, which would disinfect it as well.
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loyall
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Re: Do Mammillaria have extrafloral nectaries?

Post by loyall »

The consensus seems to be that whatever it is, it isn't nectar. So recommendation is to remove it. I am curious to know whether Mammillarias are the only cactus species in which unpollinated flowers shrivel and shrink, leaving small marks(scars).
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loyall
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Re: Do Mammillaria have extrafloral nectaries?

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I attempted to remove one of the brown spots. It was not possible to insert a cotton sway between the radial spines, so I opted for a straight pin, and scraped off a very tiny bit of brown. It was sticky. I should mention that of about thirty flower bud scars left over from February's bloom, only three showed the tiny brown goo. Then I tried and succeeded in dislodging the white bud scar under the brown goo. Removing this tiny white plug left a small hole in the plant stem which I hope will not cause any problem. Here is a photo below of this plug shaped bud reminant, with pencil lead for comparison. I am confident now that these brown spots are nothing to bo concerned about.
M microheliopsi_20220624_02.jpg
M microheliopsi_20220624_02.jpg (81.8 KiB) Viewed 286 times
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greenknight
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Re: Do Mammillaria have extrafloral nectaries?

Post by greenknight »

Mammillaria flowers shrivel and shrink like that even if they are pollinated. Fruits begin to develop within the body of the cactus and emerge seemingly out of nowhere some time later - except for some species which are cryptocarpic, whose fruits remain hidden withing the body of the cactus. See: https://www.cactus-art.biz/note-book/Di ... tocarp.htm

I've never seen one ooze sticky goo like that before, but otherwise this is normal. That old flower you dug out doesn't look rotten, so I guess there's no problem. I still think it would be a good idea to clean the wound with peroxide.
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MrXeric
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Re: Do Mammillaria have extrafloral nectaries?

Post by MrXeric »

loyall wrote: Fri Jun 24, 2022 2:59 pm I am curious to know whether Mammillarias are the only cactus species in which unpollinated flowers shrivel and shrink, leaving small marks(scars).
Probably, but I can't say I've seen every cactus species flower to verify. :lol: What I can say with certainty is that not all Mammillaria/Cochemiea "absorb" their spent flowers. Some species leave their flowers out to dry and fall off on their own
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greenknight
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Re: Do Mammillaria have extrafloral nectaries?

Post by greenknight »

There are over 200 species just of Mammillaria, I'm sure I haven't seen them all. Apparently there can be some variation even on the same plant - I found a page that shows M. pectinifera expelling some fruits while retaining others: https://www.researchgate.net/figure/Pho ... 1_51180043

On all species of Mammillaria I am familiar with, the ovaries are withdrawn into the cactus body after blooming. Most have small flowers, the petals are insignificant after they've shriveled - you wouldn't be likely to notice if they did fall off.
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