Star Anise: A Window Into the Earliest Flowering Plants

I must admit there are few flavors I loath more than anise (and consequently licorice and fennel). Regardless of the flavor, however, I nonetheless find myself enamored by their whorled seed capsules of star anise. In an attempt to reconcile my feelings towards anise in a culinary sense, I decided to get the know the plants that are responsible for it and I am so glad that I did. As it turns out, this group of small trees and shrubs offer us a glimpse at some of the earliest branches on the angiosperm family tree.

We get star anise from the genus Illicium. Native to humid tropical understories, there are roughly 40 species scattered around southeast Asia, southeastern North America, the Caribbean, and parts of Mexico. Molecular as well as fossil evidence suggests this group diverged during the mid to late Cretaceous, not long after flowering plants came onto the scene. Indeed, along with Amborella and Nymphaeales, Illicium represent the three most basal lineages of flowering plants alive today.

To call them primitive, however, would be a serious misnomer. Because they diverged so early on, these lineages represent serious success stories in flowering plant evolution. Instead, think of them as fruitful early experiments in angiosperm evolution. Illicium has characteristics that set it out as being sister to all other flowering plants. For instance, the vascular tissues more closely resemble those of gymnosperms than they do angiosperms. Like the other basal angiosperms, Illicium blur the line between the long standing categories of monocot and dicot. They are sometimes referred to as paleoherbs. Another key diagnostic feature lies in their floral morphology.

They don't have what could be considered true petals or sepals. Instead, they have whorls of tepals, which start off sepal-like and gradually become more petal-like as you near the center of the flower. The stamens, which are laminar or leaf-like, are also arranged in a dense whorl surrounding a whorl of fused carpels. Once fertilized, each carpel gives rise to a hard, glossy seed. As the carpels mature and begin to dry, the individual capsules get tighter and tighter until at some point the seed is pinched so hard that it is ejected from a slit in the fruit in projectile fashion.

Although this research will never rectify the taste of this spice, it nonetheless has given me a new found respect and sense of awe for this genus. To look upon the fruit of Illicium is to look at a biological structure that has stood the test of time. These aren't primitive plants but rather evolutionary successes that should be admired for their unique place in the story of flowering plants.

Photo Credits: Scott Zona (http://bit.ly/1Xs6Z0Z) and Tim Waters (http://bit.ly/1PxTwSm)

Further Reading:

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