Read a Section
Four organs, the same three tissue systems. Tap, click or Tab to any region to name it, then switch to Test and see whether you can find it without the labels.
- Dermal, the outside
- Ground, the bulk
- Vascular, the plumbing
The five classes you annotate
- Xylem the cluster of big conduits in each bundle. ONE contour per bundle, about sixteen of them
- Pith the centre, inside the circle of bundles. Large polygonal cells, smooth
- Phloem fibres the cap on the outer face of each bundle. The phloem itself lies between green and red
- Cortex out to the epidermis, with diamond-shaped air spaces between the cells
- Epidermis the single outer cell layer, right at the edge
Not each conduit, which would be forty outlines. Not one ring around them all, which loses the per-bundle geometry. One outline per bundle. The individual conduits are a later step and they are one click each.
Point at the section
Every mature tissue here belongs to one of three systems: dermal outside, ground in the bulk, vascular for the plumbing. Meristems cut across that: a meristem is a tissue still dividing, and it belongs to whichever system it builds. Tap a region for the mechanism, worked examples, and the reference.
The three simple tissues
The wall is the only real difference between these three. They are not confined to the ground tissue system: xylem and phloem both contain parenchyma, and the fibre caps outside the phloem are sclerenchyma sitting inside a vascular tissue. The dermal and vascular systems also build cells that are none of the three, such as guard cells, sieve elements and vessel elements.