Vascular plants have two types of sap: raw sap and processed sap. The fundamental difference between the two is that the raw sap is a mixture of mineral salts and other substances and the processed sap is composed of glucose, water, and minerals produced by photosynthesis.
| The raw sap is a mixture of water, mineral salts, and other substances that are absorbed by the roots. | The elaborated sap is manufactured in the leaves through photosynthesis, it includes sugars, minerals, and other substances that the plant requires for its growth and development. |
| The raw sap is transported by the xylem. | The processed sap is transported by the phloem. |
Raw sap
It is the sap transported by the xylem. It consists of water, mineral elements, growth regulators, and other dissolved substances. It is transported from the roots to the leaves through the woody tubes.
The raw sap is nothing more than a compound formed by water and a variety of inorganic mineral salts that the roots absorb from the soil through the root hairs and that circulates through the woody or ascending vessels known as xylem. This sap is transported to the leaves where, by photosynthesis, it is reconverted into the processed sap.
The transport mechanism of this sap has generated strong controversies. Nowadays studies support that the sap moves upwards by the cohesion-tension theory.
Elaborated SAP
It is that sap transported by the phloem from its place of formation, whether they are green leaves and stems to the root. It is composed of water, sugars, amino acids, vitamins, organic acids, dissolved minerals, and phytoregulators. In this case, the hypothesis of pressure flow is accepted as a transport mechanism for the elaborated sap.
It is carried by the phloem, a type of plant vascular tissue. Phloem can flow bi-directionally, transporting nutrients to all the parts that the plant needs, both photosynthetic organs, and organs that are not.
