🌱 根系：植物地下的"嘴巴与锚"🌱 Root System: the Underground Mouth and Anchor
上一片我们担心濒危物种会不会消失；这一片把目光移到脚下——一棵大树站得稳、渴了能喝水，全靠土里的根系。🦠 小细胞戴上头灯，钻进了土壤。Last leaf we worried about disappearing species; this leaf looks down at our feet — how a big tree stands firm and drinks. It's all thanks to the root system. 🦠 Little Cell straps on a headlamp and digs in.
第 1 步：根的两件大事：抓稳 + 喝水Step 1: A root's two big jobs — hold on + drink
先看根怎么当树的"地基"。First, how roots work as the tree's foundation.
地上树冠越大，地下根系越广。根像一张网，把树牢牢锚在土里——大风摇得动树枝，摇不动根基。同时它还在喝水：根从土里吸收水和无机盐，再送往全身。固定和吸收，就是根的两件大事。The bigger the crown above, the wider the roots below. Like a giant net, roots anchor the tree — wind shakes branches, not the base. And they drink: roots absorb water and minerals from the soil and ship them upward. Hold on and drink — those are a root's two big jobs.
那么，根靠什么吸水？先看它的两种长相。So how do roots drink? First, meet the two basic shapes.
胡萝卜、蒲公英有一条粗壮的主根，叫直根系；小麦、葱的根像一把胡须，叫须根系。真正干活的是根尖附近细细的根毛——它们把吸收面积扩大好几倍。科学家还发现，一株黑麦的所有根连起来超过 600 千米，相当于绕操场跑 1500 圈！Carrots and dandelions grow one thick main root — a taproot system; wheat and onions grow a bushy beard — a fibrous root system. The real workers are the tiny root hairs near the tips, multiplying the absorbing surface several times over. And get this: a single rye plant's roots, laid end to end, stretch over 600 kilometres — about 1500 laps around a running track!
根不光会喝，还会存、会认路。Roots don't just drink — they store, and they find their way.
第 3 步：储粮、找水：根的生存智慧Step 3: Storing food, finding water — a root's survival wisdom
胡萝卜、红薯把叶子造出的糖存进根里，胖成"地下粮仓"——储藏根。根还会认路：顺着重力往下扎（向地性），朝着湿润的地方长（向水性）。没有眼睛，也能自己找到水和安稳的位置。Carrots and sweet potatoes pack the sugars made by leaves into their roots, swelling into underground pantries — storage roots. Roots also read their way: they grow down with gravity (gravitropism) and bend toward moisture (hydrotropism). No eyes, yet they find water and a firm footing on their own.
🎮 你来当灌溉实验员（约 1 分钟）🎮 Your turn: the irrigation bench (1 minute)
小细胞把三株植物搬上实验台。调土壤湿度、换根的类型、开关根毛，看吸水速率怎么变，完成 4 张实验单。Little Cell sets three plants on the bench. Adjust soil moisture, switch root type, toggle root hairs — watch the absorption rate and finish 4 lab sheets.
一句话记住它：根系 = 植物的"嘴巴 + 船锚"：根毛负责吸，粗根负责抓，储藏根负责存。Remember it in one line: a root system is the plant's mouth and anchor — hairs absorb, thick roots hold, storage roots stockpile.
根的两件大事：固定植株、吸收水和无机盐Two big jobs: anchoring the plant and absorbing water & minerals直根系一条主根（胡萝卜）；须根系一把细根（小麦）；根毛把吸收面积扩大好几倍Taproot (carrot) vs fibrous roots (wheat); root hairs multiply the absorbing surface储藏根囤糖（萝卜、红薯）；根还会向地、向水，自己"找路"Storage roots hoard sugar; roots grow down and toward water on their own
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
Back to tree
