Nectar in Roses?

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Re: Nectar in Roses?

by roseseek » Tue Jun 18, 2019 12:48 am

Thank you.

Re: Nectar in Roses?

by Karl K » Mon Jun 17, 2019 11:45 pm

roseseek wrote:
Mon Jun 17, 2019 10:13 pm
Where is this "nectariferous ring contracting its opening" supposed to be, Karl?
Nice picture of R. minutifolia.
The disk is the ring around the orifice (where the styles poke through).

In Spiraea the hypanthium supports a nectar-producing "disk" which is ring-shaped and may have lobes as it does here. The stamens arise between the petals and the disk.
Image

http://bulbnrose.x10.mx/Roses/breeding/ ... pment.html

Re: Nectar in Roses?

by roseseek » Mon Jun 17, 2019 10:13 pm

Where is this "nectariferous ring contracting its opening" supposed to be, Karl? I harvest many dozens of Minutifolia blooms annually for pollen and I have never seen anything resembling anything like what that sounds like. That is based upon "molesting" flowers from the California Otay Mesa form; "Pure Bea" white Mexican form; UC Berkeley Mexican form and the Mexican seedling raised by Michael Tallman and Don Gers of Santa Rosa, CA.
DSCN7485.JPG
DSCN7485.JPG (69.34 KiB) Viewed 214 times
Look at Help Me Find in the photos section. I've posted some very up close and personal shots of it there.
https://www.helpmefind.com/rose/l.php?l=21.284642

Nectar in Roses?

by Karl K » Mon Jun 17, 2019 11:22 am

I have long believed that roses never produce nectar. That's what I've read many times. Insects that visit roses are there to collect pollen.

This fact seems to explain why the "female" flowers of Rosa setigera produce some pollen. Without pollen, these flowers might be ignored.

Heslop Harrison (1921) wrote, "Unless the shining secretion on the exposed disk of the Eucaninae, Agrestes and Tomentosae is nectar the Rosae do not secrete that substance." He knew much more about roses than I ever will, so I had no reason to doubt him.
http://bulbnrose.x10.mx/Roses/breeding/ ... s1921.html

But sometimes knowledgeable people are overly broad in their pronouncements. This may be an example, because in describing the flower of Rosa minutifolia, Engelmann (1882) mentioned, "a thick nectariferous ring contracting its opening..."
http://bulbnrose.x10.mx/Roses/breeding/ ... s1887.html

I have not seen this species, so I can neither confirm nor contradict Engelmann's description. Has anyone noticed nectar on the disks of R. minutifolia or its close relatives?

And while I'm on the subject of R. minutifolia, Engelmann also wrote, "This species is quite peculiar among its American congeners, and even among the roses of the Old World, so that it is difficult to determine its true position. In aspect and habit it comes nearest to the Pimpinellifoliae on account of its single bractless flowers, its numerous acicular spines, and its small leaves; but it recedes in its pinnatifid calyx-lobes."

Modern DNA evidence agrees in placing this species near the diploid Pimpinellifoliae. And it is interesting to note that DNA also places R. roxburghii near the same group. Someday it may seem reasonable to combine Pimpinellifoliae, Minutifoliae and Microphyllae as a single group.

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