The root is usually the first organ which emerges from the seed. However, because roots spend most of their time below ground, they are understudied and underappreciated. So are the Rhizologists who slave away in anonymity trying to unlock the secrets of the root!! Root systems can be as extensive or more extensive than shoot systems. Roots are generally nonphotosynthetic. However, a few, like a small orchid I spotted in Puerto Rico, are capable of photosynthesis and in this particular case, the root is the major source of photosynthate. This orchid grows in an extremely dry (xeric) environment and does not produce leaves. A stem is only produced when flowering occurs and it is ephemeral (short-lived). The roots are decidedly green and they have velamen. The velamen may serve a protective and regulatory function with regards to water loss and photosynthesis. It may act like the large scales of Tillandsia, which are opaque when dry and translucent when wet.
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Tap root (Carrot) & Fibrous root system Scallion |
A Tap root has a dominant primary root and lateral roots which are produced in a regular sequence. |
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Fibrous root systems do not have a dominant Primary root. They have many principal roots which appear to be equivalent. Branching in a Fibrous Root system may appear to be be less organized than in a Tap Root system. |
