Rose Reproduction
Part 5
What is taxonomy? Part 1 | Rosids Part 2 | genus Rosa Part 3
| Rose Species Part 4 | Rose reproduction Part 5 | Native Rose Plant Ethnobiology Part 6 | Bibliography | New Wild Roses of Saskatchewan and How to Tell them Apart
How would one describe a rose hip?
The rose hip or fruiting body is referred to as an aggregate fruit which contains many true seeds or achenes within it. These small seeds or nutlets are pendulous with a size of about 3-4 mm. Pendulous derives from the Latin pendulus ‘hanging down.’ A rose hip features an expanded hypanthium (aka floral cup), which is a structure where basal portions of the calyx, the corolla, and the stamens unite with the receptacle to form a cup-shaped tube to encircle around the nutlets (seeds or achenes).
The botanical term calyx arises from the Greek kalux ‘case of a bud, husk’, and is related to kaluptein ‘to hide’. The species Rosa will first use the calyx as a case ‘to hide” and protect the rose bud as it develops. The calyx surrounds the corolla, and is typically divided into lobes called sepals. The sepals emerge out of the apex or top of the red to orange coloured rose hip fruiting body.
The perianth is the botanical term for the envelope and has two separate units arising from a central point of origin (concentric). Perianth arises from two roots, Greek peri ‘around’ + anthos ‘flower’. The outer perianth is termed the calyx, and the calyx may be divided into sepals. The inner perianth is the corolla. The calyx is cup-shaped or urn-shaped, with a constriction at the top or the throat. Imagine a small crown, garland or a wreath made of petals, and that is a corolla, from the Latin corolla meaning small garland, little crown, chaplet or wreath.
Perfect flower
Now, then the interesting thing about roses, are that though the plants may arise from a rhizomatous root producing clones growing within a rose thicket. The clones or individual Rose plants which are seen above ground have perfect flowers (male and female organs in the same flower) so they are neither dioecious (having male flowers on one plant and female flowers on a different plant like the trembling aspen Populous tremuloides), nor monoecious (having male flowers and female flowers on the same plant).
Delve into the diversity between the ways in which the trembling aspen and the native rose bushes reproduce. Compare -find ways that they are similar and contrast -explore ways that they are different.
Male reproductive organ the Androecium.
The stamens are the yellow pollen bearing organ of a flower, from the Latin stamen, foundation in weaving, the thread of the warp, from Proto-Indo-European steh₂– “stand”, and from Gothic stoma, Sanskrit Sthaman, “Place, strength.” The stamens in a flower are collectively called the androecium. A stamen will feature an anther and a filament, Filament derives from classical Latin filum, meaning “thread” Anther derives from French anthère, from classical Latin anthera, meaning “medicine extracted from the flower” in turn from Ancient Greek ἀνθηρά, feminine of ἀνθηρός, “flowery”, from ἄνθος, “flower.” Androecium derives from Ancient Greek ἀνήρ meaning “man”, and οἶκος meaning “house” or “chamber/room”.
Female reproductive organ, the Gynoecium.
Rose plants have perfect flowers (male and female organs in the same flower), and therefore, they may be referred to as hermaphroditic, or bisexual. The male organs are the stamens, and the female organs are the carpels or pistils making up the fertile portion of the flower. The stamen consists of anther and filament as mentioned earlier, and the pistil features the stigma, style and ovary. Together, the stigma, style and ovary are referred to as the pistil and make up the female organ of the flower, the gynoecium. The male organ of the rose is the androecium, and the female organ the gynoecium.
Perigynous flower.
A rose, besides featuring a perfect flower, is also termed a perigynous flower. Perigynous comes from two Greek words as roots, peri- ‘around’ + gunē ‘woman.’ This perigynous term describes the sepals, petals, and stamens at the same level ‘around’ the edge or rim of the hypanthium with the ovary below. The ovary wall, becomes the fleshy part of the rose hip. The floral parts of the ovary are fused into a cup, referred to as the hypanthium which surrounds the ovary. Perigynous flowers are often referred to as having a half-inferior ovary (or, sometimes, partially inferior or half-superior). This arrangement is particularly frequent in the rose family.
Pollination.
Several taller stamens surround the shorter styles in the central area of the bloom. Roses produce yellow pollen held on pollen sacs called anthers reaching up high from the center of the rose blossom on the tips of filaments. A pollinator insect will fly around to feed on the nectar, and some of the pollen rubs off onto the legs and body of the pollinator. The rose flowers also have a stigma, which receives the pollen on the sticky stigma carpel situated at the tip of the style. When the insect flies off to the next flower, it is pollinated when the pollen sticks to the top of the pistil. The style connects the ovary and the stigma of the rose flower. The ovary, thus pollinated will then begin producing seeds. At the top of the rose stem, the “receptacle” begins to grow from the seeds being created within the ovary contained within it. Another name for the receptacle is the hypanthium.
The flower bloom
If a rose has more than one blossom, the inflorescence type is a cyme, which means each axis of the peduncle blooms before the flowers lower down on the stem. Additionally, each bloom (inflorescence) is stellate, or star shaped.
Reproduction methods
Reproduction of these native rose plants takes place by four methods. Roses can reproduce by
- seed and pollination in the ‘perfect flower’
- by suckering through root rhizomes
- sprouting
- layering.
Rose Pollination Matching Sheet
Activity
Place the following labels on the first picture at the top of the page.
- Petal (Edge of petals are showing)
- Sepals (Edge of sepals are showing)
- Stamens
- Filament
- Anther sacs holding the yellow pollen
- Pistil
- Stigma
- Style
- Ovary
- Achenes, seeds or nutlets
When the bees and pollinating insects come to the native roses is it day or night?
When a trembling aspen (Populous tremuloides) is compared to a native rose plant, would pollinating insects go to both the aspen tree and the rose bush?
How does the structure of the hypanthium help the rose bush to survive? Would a rose bush do as well with a winged seed that was carried off in the wind?
Why do rose petals fall off shortly after pollinating season?
How are the rose bushes benefited by a visit from a pollinating insect?
Can you hear a bee buzzing when they are collecting pollen from a flower? Why or why not?
What safety assessments need to be made while observing pollinating insects?
Are bees the only insects which are capable of pollinating rose bush flowers?
Can bees pollinate rose bush flowers in September? Why or why not? What happens to bees over the winter months?
Will pollinating insects continue to pollinate the rose bush flower if humans are around? If other animals are nearby?
Consider the position of the stamens, and pistils in the hypanthium of the rose flower. Why do the stamens and pistils rise out above the petals of the rose bush flower?
If you were as small as an insect, how would the stamens and pistils look as the insect crawled along the petal, and observed the stamens and pistils from the side?
How does the colour of the yellow pollen in the anther sac affect the visibility to pollinating insects?
The taxonomic sub-family Rosoideae describes those plant genera bearing aggregate fruits containing seeds, small achenes or drupelets, and the fleshy part of the fruit is the female reproductive organ of a flower, consisting of an ovary, a stigma, and a style. Does it help to learn about the hypanthium, and how the rose flower is pollinated to understand how the fleshy fruit grows and develops into a rose hip?
As pollinating insects such as bees visit the rose bush flowers, what kind of behaviour takes place? Draw a picture of a pollinating insect, and how the unique nature of the hypanthium helps them to collect pollen.
Have you been aware of another plants that have a similar pollinating system?
If the Richard St. Barbe Baker Afforestation Area and George Genereux Urban Regional Park forest communities had no humans in them, and they were preserved habitats, what effect would that have on the native rose bushes? Are the native rose bushes in danger of extirpation or extinction, or are they thriving? Why? Does human activity affect the pollination of native rose bushes?
How do light and sounds in and around the Richard St. Barbe Baker Afforestation Area and George Genereux Urban Regional Park forest communities affect the native rose bush pollination? Do pollinating insects become more or less active under artificial light? Do rose bush flowers close up in the dark?
If you were a bug walking on a rose petal, would it be easy or hard to walk along the surface of the petal?
Does weather affect the pollination of rose flowers? Do pollinating insects fly around in a rain storm? in a hail storm? during a light rain sprinkle?
Native rose plants have four methods of reproduction, are they asexual, or sexual? Does pollination and creating achenes in the fruiting body work better for the native roses, or does suckering via rhizomatous roots?
Do rose plants have other methods of reproduction?
Learning about how a rose bush creates seeds by being pollinated, how is the flower shape important to the survival of the rose bush?
How large are the seeds compared to the rose bush plant?
How does the rose bush get the seeds out of the rose hip after the flower has been pollinated?
Create a story of the relationship between bees and rose bush flowers.
How are the bumble bees benefited from flying over to the rose bush flowers?
Do both the trembling aspen and the rose bush have leaves, roots, stems. flowers, fruits and seeds?
Every act of kindness benefits the giver, as well as the receiver.
-Katrina Mayer
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For more information:
Richard St. Barbe Baker Afforestation Area is located in Saskatoon, Saskatchewan, Canada north of Cedar Villa Road, within city limits, in the furthest south west area of the city. 52° 06′ 106° 45′
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Part SE 23-36-6 – Afforestation Area – 241 Township Road 362-A
Part SE 23-36-6 – SW Off-Leash Recreation Area (Richard St. Barbe Baker Afforestation Area ) – 355 Township Road 362-A
S ½ 22-36-6 Richard St. Barbe Baker Afforestation Area (West of SW OLRA) – 467 Township Road 362-A
NE 21-36-6 “George Genereux” Afforestation Area – 133 Range Road 3063
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“St. Barbe’s unique capacity to pass on his enthusiasm to others. . . Many foresters all over the world found their vocations as a result of hearing ‘The Man of the Trees’ speak. I certainly did, but his impact has been much wider than that. Through his global lecture tours, St. Barbe has made millions of people aware of the importance of trees and forests to our planet.” Allan Grainger
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Richard St. Barbe Baker Afforestation Area. George Genereux Urban Regional Park. 