– Lateral Meristems:
– Secondary growth in vascular plants is driven by the cork cambium and vascular cambium.
– These lateral meristems increase the width of plant roots or stems, not their length.
– Continuous cell production by lateral meristems leads to the thickening of stems, producing wood in woody plants.
– Plants with secondary growth often develop a cork cambium to protect against water loss.
– Over time, the cork cambium can create a protective layer, as seen in cork oak.
– In Nonwoody Plants:
– Secondary growth is not exclusive to woody plants; it also occurs in nonwoody plants like tomato, potato tuber, carrot taproot, and sweet potato.
– Some long-lived leaves exhibit secondary growth.
– Abnormal Secondary Growth:
– Palms, like Roystonea regia, enlarge their trunk diameter through parenchyma tissue division and enlargement, not typical secondary growth.
– Anomalous secondary growth deviates from the conventional pattern of vascular cambium producing secondary xylem and phloem.
– Monocots have lost ancestral secondary growth, with some exhibiting anomalous secondary growth or primary gigantism.
– Certain monocot stems, such as Yucca and Dracaena, show abnormal secondary growth with cambium producing internal vascular bundles and external parenchyma.
– See Also:
– Bark, cambium, root, stem, and tylosis are related to secondary growth in plants.
– Dendrochronology and herbchronology are fields that study plant growth rings and aging.
– References:
– Studies like Thompson and Heimsch (1964) and Ewers (1982) provide insights into secondary growth in plants like tomato and Pinus longaeva.
– Mauseth’s “Botany: An Introduction to Plant Biology” (2003) covers various aspects of plant growth and development.
– Esau and Cheadle (1969) delve into secondary growth in Bougainvillea, highlighting anomalies.
– Simpson (2005) notes the absence of secondary growth in Arecaceae (Palmae) plants.
– Scientific literature like Augusto and Garófalo (2004) explores nesting biology and social structure in specific plant species.
In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips of stems and roots, causing them to elongate, and gives rise to primary tissue. Secondary growth occurs in most seed plants, but monocots usually lack secondary growth. If they do have secondary growth, it differs from the typical pattern of other seed plants.
The formation of secondary vascular tissues from the cambium is a characteristic feature of dicotyledons and gymnosperms. In certain monocots, the vascular tissues are also increased after the primary growth is completed but the cambium of these plants is of a different nature. In the living pteridophytes this feature is extremely rare, only occurring in Isoetes.