41. This consisted of a cylindrical strand of xylem , surrounded by a region of phloem. 42. With bacterial vascular diseases, the infection is spread within the plants through the xylem . 43. Wood is primarily composed of xylem cells with cell walls made of cellulose and lignin. 44. Secondary xylem is commercially important as wood. 45. But certain cells don't transform into xylem and phloem and remain as such. 46. It moves towards the vertically aligned xylem . 47. Xylem comprises three business units-Water Solutions, Analytics, and Applied Water Systems.48. Some xylem cells carry water and nutrients up from the roots, while others store food. 49. Without proof that sizable negative pressures exist in the xylem , the pull theory remains speculative. 50. It also allows plants to draw water from the root through the xylem to the leaf.
