The surfaces of the wooden pieces are strongly attacked. The single cells can be scraped off after washing of the preparation and examined under the microscope. Let us start with a portrait of the different cell types . Tracheids are the chief water-conducting elements in gymnosperms and seedless vascular plants. They can also be found in angiosperms.
Tracheids are elongated cells, closed at both ends.
In average are they 1 mm long. They are regarded as the prototype of prosenchymatic cells, since the cell's ends are pointed and real final walls are missing. Tracheids look often square in cross-section, the lignified secondary wall is relatively thin. Their entire cell surface is evenly coated. They occur solitarily, statistically scattered, arranged in turns around the middle axis or grouped together.