Friday, April 20, 2012

Lupine: the state flower of Texas

Species name: Lupinus sp.

Common name: Lupin, lupine

Location: Nova Scotia (second photo from Wikipedia showing the flowers of various ornamental species)

The lupine (or lupin, as this plant is referred to outside of North America) is native to a wide variety of locations from all continents. Now, various species can be found worldwide and only a few can be distinguished by leaf shape and leaf characteristics alone (this isn't one of them--hence "Lupinus sp."). Lupines are part of the bean family, and have characteristic bean flowers and also share the most sought-after characteristics of beans as agricultural crops: they have high concentrations of protein and oil in their seeds, and have symbiotic bacteria in their roots that fix nitrogen. This biologically-available nitrogen is then released to the plant in return for sugars and oxygen, where it can be used by the plant in photosynthesis to make more sugar (and in respiration to make energy). For this reason, lupines are very popular in some agricultural systems to be planted alongside crops that require large amounts of nitrogen fertilizers like corn and wheat. These types of plants are referred to as "green manure". There are about 280 species in the genus Lupinus, and the Texas Bluebonnet (Lupinus texensis) is the state flower of Texas.

Certain species of lupine can be eaten, but others are quite toxic. If you don't know what species is growing in your back yard, it is best not to try to consume it. Mediterranean dishes are ones that are most likely to contain lupine seeds: in Portugal and Spain they are consumed dry-roasted like peanuts with beer, in Lebanon they are served as a pre-dinner snack and called "Termos", in the Andes (OK, so not part of the Mediterranean) they are called "tarwi" and eaten like any other bean, in Germany they are often ground and used as a meat substitute. The "bitter" varieties of lupine have high concentrations of toxic alkaloids in their seeds which can cause a temporary paralysis in the lower limbs, muscle decay or atrophy of the buttocks (which can be permanent), and cell death in motor neurons (which would lead to permanent paralysis).

Like most plants that have very broad geographical ranges, there are ornamental species of lupine that have been introduced to North America over the years (accidental or on purpose) that have escaped and have become invasive. There are certain areas in the southern USA that are completely covered by lupines in roadside ditches and sometimes even growing up in the front lawn. While the flowers are incredibly attractive, if they're growing where you don't want them it's definitely not ideal. 

One last special characteristic to note about these plants is that they are an important food crop for the larvae (i.e. caterpillars) of some butterfly species, and the flowers can serve as important nectar sources for many pollinating insects (including some butterflies). If you are going to create a butterfly garden, adding lupines would be a great idea; just make sure you're planting native species that are food sources for the native butterflies that will be visiting your garden or you might be disappointed in the results!