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Author Topic: Apocynaceae pollination  (Read 236 times)

KarenRei

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Apocynaceae pollination
« on: February 01, 2018, 05:53:47 PM »
So, I'm having trouble tracking down data on pollination of Apocynaceae species - in particular, what's monoecious / (functionally) dioecious and (if monoecious) what's self-fertile.  And in particular:

 * Ancylobothrys
 * Carissa
 * Landolphia
 * Saba
 * Tabernaemontana (T. elegans specifically)
 * Willughbeia

So far, I've found lots of references to many species having hermaphroditic flowers, so it's looking like this is a pretty standard feature of Apocynaceae.  I've not yet found a species confirmed to be monoecious.  Of a couple hundred species in thefamily checked, I've found several (but still quite a small fraction of the total) listed as dioecious / functionally dioecious:

 * Rauvolfia sellowii
 * Rauvolfia vomitoria
 * All three Fockea species (F. angustifolia, F. edulis, F. multiflora)
 * Carissa macrocarpa
 * Allamanda cathartica

Should I just assume that as a general rule, Apocynaceae are dioecious?  Does anyone have any more specific info about specific species?  I've seen a number of threads hearing about people complaining about growing landolphias or willughbeias that got huge but never set fruit, and I can't help but wonder if this is the reason.
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polux

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Re: Apocynaceae pollination
« Reply #1 on: February 02, 2018, 02:31:56 PM »
I have only Carissa macrocarpa, it fruits without problems. Some Apocynaceae may need special pollinators like moths. I dont know if it is the case of Carissa, but flowers have strong delicate scent like jasmine.

KarenRei

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Re: Apocynaceae pollination
« Reply #2 on: February 02, 2018, 07:22:34 PM »
I have only Carissa macrocarpa, it fruits without problems. Some Apocynaceae may need special pollinators like moths. I dont know if it is the case of Carissa, but flowers have strong delicate scent like jasmine.

Fruits with just one plant?  My understanding is that it's mostly (but not completely) functionally dioecious, as it comes in two forms: stamens the same length as the style but no pollen (female) and stamens longer than the style (technically hermaphrodite, but pollen can't readily transfer to the style and fruiting is supposedly poor compared to transferred pollen, even with pollinators.

There's a lot of really tempting apocynaceae plants (forgot to add Hancornia to the above list), but dioecy is something that one has to be careful of, so I'm trying to collect that info.
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KarenRei

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Re: Apocynaceae pollination
« Reply #3 on: April 25, 2018, 09:24:26 PM »
Just ran into one more detail describing the "general properties" of Apocynaceae which mentions:

Flowers: hermaphrodite
"Because the receptive stigmatic surface is located on the underside of the stigma, cross-pollination is the rule of the family. Self-pollination is absent."

Dioecy appears to be the exception, not the rule.  As a negative, insect pollinators seem to be required.  As a positive, its flowers appear to be quite attractive to insects, combining appearance, a strong scent, a pollen reward, and a nectar reward.  Also as a positive - while it's not mentioned - one would expect that if it's evolved such a stigma design to avoid self-pollination then it's less likely to have needed to evolve a genetic process to prevent self pollination.

ED: Oooh, jackpot!
http://edepot.wur.nl/165045

"self-incompatibility is common in Apocynaceae (Rowley, 1980") - Really?  Well, there goes my theory...   
(still reading)

Okay, here's what they report:
Wrightia tinctoria: requires an insect visit, but the flower will pollinate itself even if the insect carries no pollen
Catharanthus roseus: Autogamous, self-fertile without insects.
Plumeroideae:Usually autogamous
Tabernaemontanoideae are: Said to be always allogamous.  Yet in the two species tested, pollen from a given flower appeared to germinate anywhere on the pistil and reach the ovaries.
Amsonia orientalis: Not self-fertile (no fruit set when flowers covered)
Vinca minor: Requires pollination, generally by honey bees, to get the pollen to a place it can germinate.

Pollination generally by insects with long mouthparts - bees, butterflies, some wasp species.

Unfortunately, they didn't check any of the more interesting species, and they didn't verify that fertilized ovaries actually develop fruit with pollen from the same flower.  And when they write that self compatibility is rare, I don't think they mean genetic self-compatibility.

Hmm.... 

« Last Edit: April 25, 2018, 09:39:55 PM by KarenRei »
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