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To quote a Hants Plants (wonderful name!) workshop: "Glands – presence of glands on the underside of leaflets and on the edges can be crucial in species identification. As can the type of glands. Glands can be sweet/apple scented and large, resin scented and small, or small and unscented. Noting type of gland and where they are on a leaflet, rachis, petiole and stipule is important."
Glands can also occur on the pedicel and receptacle, and can be stalked or sessile (or on the end of acicles, which is a new word for me).
So: can someone please tell me what the glands, if any, on a rose pedicel or receptacle do / are for? Apart from making identifiers buy a 20x magnifier.
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#1 of 2 posted
28 AUG by
jedmar
I have not yet seen a study a of rose glands, however glands are also present in other plants. Here are a few statements on their function:
1. Glandular hairs are spread over the aerial vegetative and reproductive organs of the Lamiaceae. They produce essential oils which apparently protect against herbivores and pathogens. From a functional viewpoint, owing to the mode and timing of secretion, the glandular hairs may be classified into two types: (a) short-term glandular hairs, which start and end secretion rapidly, and which serve for the protection of young organs; and (b) long-term glandular hairs, in which secretory materials accumulate gradually under an elevated cuticle, and which serve for the protection of mature organs. In the flower, protection against herbivores and attraction of pollinators are both apparently achieved by glandular hairs situated on various floral parts.
2. Like plants everywhere, these species need to protect themselves from herbivores and pathogens. We may think that Mint, Sage and other plants in the Dead-nettle or Lamiaceae family, which includes Marsh Woundwort, have a lovely scent and flavour just to enhance our foods and cosmetics. In reality, they produce secondary metabolites such as oils, tannins and flavonoids in the leaves to deter and protect themselves against microbial infections and herbivores. Marsh Woundwort, although not particularly fragrant to us, is very attractive to bumblebees and so is likely to be producing volatile oils in its glandular hairs, even though we can’t detect them.
3. The accumulation of essential oils in plants is generally limited to specialized secretory structures, namely, glandular trichomes (hairs) which are multicellular epidermal glands, found in some families such as Lamiaceae, Asteraceae, and Solanaceae, and which secrete terpenes in an extracellular cavity at the apex of the trichome. Storage of terpenoids in these structures can also be used to limit the risk of toxicity to the plant itself.
So, the glands seem to be for secretion of liquid substances, either for attraction, or protection, or even reducing level of toxic substances.
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Thank you. I guess the glands that seem scentless just don't produce anything detectable by the human nose. Next question: why don't some roses have glands on the pedicel, despite being fairly closely related to those that do? And why do some have grooved pedicels? Photos lifted from the Aus. Mystery Roses booklet.
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Could someone please add the definition of the word 'calyx' to the glossary?
Online dictionary says 'calyx' refers to all the sepals of one flower. Is that correct?
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Good suggestion. Yes. Added. Thanks Nastarana.
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Hello, last year I was trying to identify two rose bushes growing both sides of an old farm's window. I presumed both bushes were the same, but on my last visit I noticed one bush produced very round hips while the other had not so perfectly round hips. Is such a variation a proof that both roses are not the same ? The bushes, or at least one of them, could be Crimson Glory ; after some days in a vase, the flowers start developing a very bad, putrid scent (also noticed on another old red rose).
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#1 of 3 posted
12 DEC 20 by
HubertG
Subtle variation like that in the shape of those hips probably isn't enough to discern the two roses are different especially if they seem identical in other respects.
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#2 of 3 posted
12 DEC 20 by
ThomasR
Thank you HuberG, your answer is helpful ! In the future I will try to have a more careful look at these roses, but they did seem to be the same to my untrained eyes. Best regards, Thomas.
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#3 of 3 posted
12 DEC 20 by
HubertG
You're welcome! And it also makes sense that they might have planted the same fragrant rose on either side of the window to allow the scent in the house.
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What are the differences between sepal and calyx?
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Mr. Collins (dictionary - my teacher on all things botanical) tells us: Sepal: any of the separate parts of the calyx of a flower. Calyx: The sepals of a flower collectively, forming the outer floral envelope that protects the developing flower bud. Corolla: the petals of a flower collectively, forming an inner floral envelope,
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