Inbotany, arosette is a circular arrangement of leaves or of structures resembling leaves.
In flowering plants, rosettes usually sit near the soil, but they can also be at the top of an otherwise leafless branch or trunk. Their structure is an example of amodified stem in which theinternode gaps between the leaves do not expand, so that all the leaves remain clustered tightly together and at a similar height. Some insects induce the development ofgalls that are leafy rosettes.[1]
Inbryophytes andalgae, a rosette results from the repeated branching of thethallus as the plant grows, resulting in a circular outline.
Many plantfamilies have varieties with rosettemorphology; they are particularly common inAsteraceae (such asdandelions),Brassicaceae (such ascabbage), andBromeliaceae. The fernBlechnum fluviatile orNew Zealand Water Fern (kiwikiwi) is a rosette plant.
Often, rosettes form inperennial plants whose upper foliage dies back with the remaining vegetation protecting the plant. Another form occurs wheninternodes along a stem are shortened, bringing the leaves closer together, as inlettuce,dandelion and somesucculents.[2] (When plants such as lettuce grow too quickly, the stem lengthens instead, a condition known asbolting.) In yet other forms, the rosette persists at the base of the plant (such as the dandelion), and there is ataproot.
Part of the protective function of a rosette like the dandelion is that it is hard to pull from the ground; the leaves come away easily while the taproot is left intact.
Another kind of protection is provided by thecaulescent rosette, which is part of the growth form of the giant herb genusEspeletia in South America, which has a well-developed stem above the ground.[3] In tropical alpine environments, a wide variety of plants in different plant families and different parts of the world have evolved thisgrowth form characterized by evergreen rosettes growing abovemarcescent leaves. Examples where this arrangement has been confirmed to improve survival, help water balance, or protect the plant from cold injury areEspeletia schultzii andEspeletia timotensis, both from theAndes.[4][5]
The rosette form is the structure, the relationship of the parts, and the variations within it, as shown in the following study from aherbarium:
As form, "rosette" is used to describe plants that perpetually grow as a rosette and the immature stage of plants such as some ferns.
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