xylem 的定义
Botany.
- a compound tissue in vascular plants that helps provide support and that conducts water and nutrients upward from the roots, consisting of tracheids, vessels, parenchyma cells, and woody fibers.
更多xylem例句
- Such a feat seemed so unlikely for the tiny insects that some scientists questioned whether xylem sap truly could be under such negative pressures.
- This strategy suggests that the negative pressures of xylem sap can exceed one megapascal.
- Extra xylem and phloem help the stem pump more food and water into the fruit, leaving less for the rest of the plant.
- Xylem, zī′lem, n. the woody part of vegetable tissue—opposed to the phlom, or bast part.
- All round the xylem and the phloëm there are many thick-walled cells.
- These vessels together with the numerous small thick-walled cells lying between the pitted vessels constitute the xylem.
- Just above the xylem there is a group of large and small thin-walled cells.
- The larger bundles are normal in every way, while in the smaller ones the xylem elements are considerably reduced.