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Lupinus

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Lupinus is a large genus of flowering plants within the Fabaceae family. This family is commonly known as the legume family.

These plants are significant for many different reasons. They serve as important food sources for humans. Many people also grow them as ornamental plants to beautify gardens. However, they can also become invasive in certain environments. For example, lupines have caused ecological problems in Iceland since the beginning of the 21st century.

The physical structure of a lupin varies depending on the specific species. Most species are herbaceous perennial plants, meaning they live for multiple years. Some species are annuals that complete their life cycle in one year. A few species grow as shrubs. One rare exception is the chamis de monte in Mexico, which grows as a tree.

The leaves are typically green or grey-green. They often feature a coating of silvery hairs. Most leaf blades are palmately divided into five to 28 leaflets. In some species from the southeastern United States, the blade is reduced to a single leaflet.

Lupins are easily recognized by their unique flower structure. The flowers grow in dense or open whorls on an erect spike. Each flower has a distinct shape similar to a pea flower. This shape includes an upper standard, also called a banner. It also features two lateral wings. The two lower petals are fused together to form a structure called a keel.

Canadian Tiger Swallowtail on Wild Lupine
Canadian Tiger Swallowtail on Wild Lupine

This specific flower shape has inspired names like bluebonnets and quaker bonnets. After flowering, the plant produces a fruit known as a pod. This pod contains several seeds. These seeds often have a bitter taste because they contain alkaloids.

Taxonomy, the science of classifying organisms, has been quite complex for this genus. In 1873, Sereno Watson divided the genus into three sections: Lupinus, Platycarpos, and Lupinnelus. Watson used habitat and the number of ovules to make these divisions. An ovule is a part of the plant that eventually develops into a seed. Later, in 1907, researchers Ascherson and Graebner expanded this work. They studied lupins from both the Eastern and Western Hemispheres. They used the number of seedbuds in the ovary as their primary criterion for classification.

Modern science currently recognizes two main subgenera within the genus. The first is subgenus Platycarpos, which includes species from the Western Hemisphere.

Lupinus angustifolius (1)
Lupinus angustifolius (1)

These plants are often found in the Andes and Cordillera mountain systems. This subgenus contains perennial, annual, and even fruticose forms. The seeds in this group are usually small with an underdeveloped embryo. The second is subgenus Lupinus, which includes 12 species from Africa and the Mediterranean. This group is characterized by having a minimum of four ovules in the ovary.

Determining the exact number of lupine species remains a challenge for botanists. The plants are highly variable, which makes them difficult to organize. Some American taxa are described as complexes rather than distinct species. Because of this variability, estimates for the total number of species range from 200 to 500. One specific authority estimates there are approximately 267 species worldwide. This uncertainty shows how much work remains for scientists studying plant evolution.

Studying the genus Lupinus provides deep insights into biological diversity. The differences in leaf texture, such as waxy coatings or pubescence, show how plants adapt to their surroundings. Even the chromosome numbers vary, with some subgenera showing counts of 36, 48, or 96. These details help scientists understand the genetic relationships between different plants. By examining these small variations, researchers can better map the history of life on Earth.

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🖼️ Images & Media (4)
File:Garbancillo (Lupinus aschenbornii) II.jpg
Garbancillo (Lupinus aschenbornii) II.jpg
File:Canadian Tiger Swallowtail on Wild Lupine.jpg
Canadian Tiger Swallowtail on Wild Lupine.jpg
File:Lupinus angustifolius (1).jpg
Lupinus angustifolius (1).jpg
File:Lupinus-pilosus-2015-Zachi-Evenor-cropped01.jpg
Lupinus-pilosus-2015-Zachi-Evenor-cropped01.jpg
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