📚 Structure of the Flower | 花的结构
Flowers are the reproductive organs of flowering plants. They allow plants to reproduce sexually by producing seeds. In KS3 CIE Science, you need to name the parts of a typical flower and explain what each part does.
花是被子植物的生殖器官。它们让植物通过产生种子进行有性生殖。在 KS3 CIE 科学课程中，你需要说出典型花的各部分名称，并解释各部分的功能。
1. The flower as a reproductive organ | 花是生殖器官
A flower is not just a decoration. It is the plant's reproductive structure. Its main job is to produce seeds after pollination and fertilisation have taken place.
花不只是装饰。它是植物的生殖结构。它的主要任务是在传粉和受精发生后产生种子。
The male parts of the flower produce pollen grains, and the female parts contain ovules. When a male gamete from pollen fuses with a female gamete inside an ovule, a seed can begin to form.
花的雄性部分产生花粉粒，雌性部分含有胚珠。当花粉中的雄配子与胚珠内的雌配子融合时，种子就开始形成。
2. The four main whorls | 四轮基本结构
A typical insect-pollinated flower has four rings of modified leaves called whorls. From outside to inside they are: sepals, petals, stamens and carpels.
典型的虫媒花有四轮变态叶，称为花轮。从外到内依次是：花萼、花瓣、雄蕊和雌蕊。
- Sepals / 花萼
- Petals / 花瓣
- Stamens / 雄蕊
- Carpels / 雌蕊
These whorls are all attached to the receptacle, which is the swollen tip of the flower stalk.
这些花轮都着生在花托上，花托是花柄顶端膨大的部分。
3. Sepals protect the bud | 花萼保护花蕾
Sepals are small, green, leaf-like parts at the base of the flower. They enclose and protect the flower bud before it opens.
花萼是花基部绿色、像叶子的小片。它们在花蕾开放前包住并保护花蕾。
In many flowers the sepals turn back or fall off after the flower opens, but their protective job is done first.
许多花开放后花萼会翻卷或脱落，但它们的保护任务已经完成。
Some sepals remain attached and may help support the petals or protect the developing fruit.
有些花萼会保持附着状态，可能有助于支撑花瓣或保护发育中的果实。
4. Petals attract pollinators | 花瓣吸引传粉者
Petals are often brightly coloured and scented. Their function is to attract insects, birds or other pollinators to the flower.
花瓣通常颜色鲜艳且有香味。它们的功能是吸引昆虫、鸟类或其他传粉者到花上。
Some petals have nectar guides, which are patterns that point pollinators towards the nectar. This increases the chance that pollen will be transferred.
有些花瓣有蜜导，即引导传粉者找到花蜜的图案。这增加了花粉被传递的机会。
Not all petals are large and colourful. Wind-pollinated flowers often have small, dull petals or no petals at all.
并非所有花瓣都大而鲜艳。风媒花通常花瓣小、不鲜艳，甚至没有花瓣。
5. Male parts: the stamens | 雄性部分：雄蕊
Each stamen has two parts: a thin filament and an anther at the tip. The anther produces pollen grains, which contain the male gametes.
每个雄蕊由两部分组成：细长的花丝和顶端的花药。花药产生花粉粒，花粉粒中含有雄配子。
The filament holds the anther in a position where pollen can be picked up by insects or released into the wind.
花丝将花药固定在适合昆虫带走花粉或花粉释放到风中的位置。
When the anther is ripe, it splits open and releases pollen. This process is called dehiscence.
花药成熟后会裂开并释放花粉。这个过程称为开裂。
6. Female parts: the carpel | 雌性部分：雌蕊
The female part of a flower is called the carpel or pistil. A carpel has three main regions: the sticky stigma, the style and the ovary.
花的雌性部分称为心皮或雌蕊。心皮有三个主要部分：粘性的柱头、花柱和子房。
The stigma is sticky so that pollen grains can attach to it. The style is a tube that connects the stigma to the ovary.
柱头具有粘性，使花粉粒能够附着在上面。花柱是连接柱头和子房的管道。
The ovary contains one or more ovules. Each ovule contains a female gamete called an egg cell.
子房内含有一个或多个胚珠。每个胚珠含有一个雌配子，称为卵细胞。
After fertilisation, the ovule becomes a seed and the ovary usually becomes a fruit.
受精后，胚珠发育成种子，子房通常发育成果实。
7. Receptacle and nectary | 花托与蜜腺
The receptacle is the swollen end of the flower stalk. All the other flower parts are attached to it.
花托是花柄顶端膨大的部分。花的其他所有部分都着生在上面。
Many insect-pollinated flowers also have a nectary at the base of the petals or stamens. It produces sugary nectar, which rewards pollinators.
许多虫媒花在花瓣或雄蕊基部还有蜜腺。蜜腺产生含糖的花蜜，作为对传粉者的奖励。
While drinking nectar, insects brush against the anthers and stigma. This helps transfer pollen.
昆虫在吸取花蜜时会擦过花药和柱头。这有助于传递花粉。
8. Pollination | 传粉
Pollination is the transfer of pollen from the anther to the stigma. It must happen before fertilisation can occur.
传粉是花粉从花药传到柱头的过程。它必须发生在受精之前。
Self-pollination occurs when pollen lands on the stigma of the same flower or another flower on the same plant. Cross-pollination occurs when pollen is transferred to a flower on a different plant of the same species.
自花传粉是指花粉落在同一朵花或同一株植物另一朵花的柱头上。异花传粉是指花粉被传到同种另一株植物的花上。
Cross-pollination usually produces seeds with more genetic variety, so many flowers have adaptations that encourage it.
异花传粉通常产生遗传多样性更大的种子，因此许多花具有促进异花传粉的适应性特征。
9. Insect-pollinated vs wind-pollinated flowers | 虫媒花与风媒花
Insect-pollinated flowers have large, bright petals, scent and nectar. Their pollen is often sticky or spiky so it can cling to insects. The stigma is usually small and sticky.
虫媒花有宽大、鲜艳的花瓣、香气和花蜜。它们的花粉通常有粘性或有刺，便于附着在昆虫身上。柱头通常小而粘。
Wind-pollinated flowers usually have small, dull petals or no petals. They produce huge amounts of light, smooth pollen. Their stamens hang outside the flower and their stigmas are large and feathery to catch pollen from the air.
风媒花通常花瓣小、不鲜艳，甚至没有花瓣。它们产生大量轻而光滑的花粉。它们的雄蕊悬在花外，柱头大而羽毛状，以便从空气中捕捉花粉。
Table 9.1 compares the two types of flower.
表 9.1 比较了这两种类型的花。
| Feature | Insect-pollinated | Wind-pollinated |
| Petals | Large, bright | Small, dull or absent |
| Scent and nectar | Usually present | Usually absent |
| Pollen | Sticky, spiky, small amounts | Light, smooth, huge amounts |
| Stigma | Small, sticky | Large, feathery |
表 9.1 虫媒花与风媒花的对比。
10. From flower to fruit | 从花到果实
After pollen lands on the stigma, a pollen tube grows down the style into the ovary. The male gamete travels down this tube and fuses with the egg cell inside an ovule. This fusion is fertilisation.
花粉落到柱头后，花粉管沿着花柱向下生长进入子房。雄配子沿花粉管向下移动，与胚珠内的卵细胞融合。这种融合就是受精。
The fertilised ovule develops into a seed. The ovary develops into a fruit, which protects the seeds and helps with dispersal.
受精后的胚珠发育成种子。子房发育成果实，果实保护种子并帮助传播。
Sepals, petals and stamens usually wither and fall off after fertilisation because their jobs are complete.
受精后，花萼、花瓣和雄蕊通常会凋谢脱落，因为它们的工作已经完成。
11. Key vocabulary table | 核心词汇表
The table below summarises the main flower parts and their functions.
下表总结了花的主要部分及其功能。
| Part | Function | 中文 |
| Sepal | Protects the flower bud | 花萼：保护花蕾 |
| Petal | Attracts pollinators | 花瓣：吸引传粉者 |
| Anther | Produces pollen | 花药：产生花粉 |
| Filament | Supports the anther | 花丝：支撑花药 |
| Stigma | Receives pollen | 柱头：接受花粉 |
| Style | Connects stigma to ovary | 花柱：连接柱头和子房 |
| Ovary | Contains ovules; becomes fruit | 子房：含胚珠；发育成果实 |
| Ovule | Contains female gamete; becomes seed | 胚珠：含雌配子；发育成种子 |
| Receptacle | Supports all flower parts | 花托：支撑所有花部 |
| Nectary | Produces nectar | 蜜腺：产生花蜜 |
12. Common misunderstandings | 常见误解
One common mistake is to call the whole female structure the 'ovary'. The ovary is only the swollen base; the carpel includes stigma, style and ovary.
一个常见错误是把整个雌性结构称为“子房”。子房只是膨大的基部；心皮包括柱头、花柱和子房。
Another mistake is confusing pollination with fertilisation. Pollination is the transfer of pollen. Fertilisation is the fusion of gametes. Pollination comes first, but they are not the same.
另一个错误是混淆传粉和受精。传粉是花粉的转移。受精是配子的融合。传粉先发生，但它们不是一回事。
Students also sometimes think all flowers are brightly coloured. Wind-pollinated flowers are often green, small and easy to miss.
学生有时还认为所有花都颜色鲜艳。风媒花通常绿色、细小，容易被忽略。
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