There's bacteria, there's algae..., vascular plants.

有细菌，有藻类，有物。

Another type of seedless vascular plant is ferns, also known as monilophytes.

另一种无物是蕨类物，也被称为单生物。

We're talking bryophytes and seedless vascular plants, the categories that include mosses and ferns, liverworts, and more.

我们说的是苔藓物和无物，这类物包括苔藓、蕨类、苔类等。

As you can tell, bryophytes and seedless vascular plants are not simply low-to-the-ground lurkers.

正如你所知，苔藓物和无物并不是简单的下潜伏者。

Although many of the early seedless vascular plants have gone extinct, you can still find some of them growing today.

虽然许多早期的无物已经灭绝了，但你仍然可以发现它们中的一些在今天生长。

When Prototaxites first arrived on the scene, 420 million years ago, vascular plants had just begun to colonize the land.

4.2 亿年前，原紫杉首次出现时，束物才刚刚开始在这上定居。

Huge forests full of ferns, mosses, and some of the earliest vascular plants had taken over much of the planet.

长满蕨类物、苔藓和一些最早的束物的巨大森林占据了球的大部分区。

Well, the bryophytes and seedless vascular plants were some of the first plants to arise from that event — and many of them still exist today!

苔藓物和无物是第一批从那次事件中产生的物，其中许多今天仍然存在！

But, they were the first plants to form true roots, stems, and leaves that contain vascular tissue, so they're considered the first vascular plants.

但是，它们是第一批形成真正的根、茎和含有组织的叶子的物，所以它们被认为是第一批物。

Next time, we'll be using these tools to uncover the history of plants, starting with bryophytes and seedless vascular plants, some of the earliest plants on Earth.

下节课，我们将用这些工具来揭开物的历史，从苔藓物和无物开始，它们是球上最早的物。

So big, complex life on land -- like vascular plants -- probably wouldn't have been possible if Tortotubus and its fungal predecessors hadn't prepared the land first.

如果 Tortotubus 及其真菌前辈没有首先准备，那么陆上如此庞大、复杂的生命——如物——可能是不可能存在的。

So, a few hundred million years later, a cousin of the bryophytes showed up, Seedless Vascular Plants forming another branch on the plant family tree: seedless vascular plants.

因此，几亿年后，苔藓物的表亲无物出现了，形成了物家族树的另一个分支：无物。

The nutrients themselves could come from conventional crops, but Dr Post also has plans to use algae, which grow faster than vascular plants, to provide the necessary amino acids, sugars and fats.

那些营养物质可以从普通农作物中获取，但Post博士计划使用藻类，因为它们比那些物长的要快，以此提供所需的氨基酸、糖类和脂肪。

The three main organs that comprise a plant body are stems, leaves, and roots, and their presence is one of the defining characteristics of a category called vascular plants.

组成物体的三个主要器官是茎、叶和根，它们的存在是物的一个决定性特征。

But lycopods were also the earliest vascular plants, which means they were the first plants to contain xylem, a special tissue that moves water and nutrients from the roots to the leaves.

但石松属也是最早的物，这意味着它们是最早含有木质部的物，木质部是一种特殊的组织， 可以将水分和养分从根部输送到叶子。

On top of that, seedless vascular plants — and all plants that evolved after them — have a dominant sporophyte, meaning that what we tend to recognize as the plant is actually its sporophyte generation.

最重要的是，无物——以及在它们之后进化的所有物——都有一个显性的孢子体，这意味着我们倾向于认为的物实际上是它的孢子体一代。

Having a dominant sporophyte introduced lots of advantages — like, while the spore-making generation of a bryophyte couldn't grow very far off the ground; the sporophytes of seedless vascular plants could grow much taller and larger, with more room for spore-producing organs.

拥有一个优势孢子体带来了很多好处——比如，苔藓物的产孢体不能长得离面很远；而无物的孢子体可以长得更高更大，有更多的空间容纳产孢器官。