Thermopsis lupinoides (Thermopsis lanceolata)
Stiffly ascending stems terminate with upright spikes of bright yellow; nectar-rich pea flowers. Thermopsis lupinoides (Thermopsis lanceolata) is a very attractive; if little known species. Non invasive. to 80cm. Sun (I see some books make T.lanceolata the correct name for this plant, whilst the newest Plant Finder (2015) splits them again into two species.)
Thermopsis is a member of the Fabaceae – The bean family, which is the third largest family of flowering plants with over 650 representative Genera (16,000 plus species) in nearly every corner of the Earth in a huge variety of habitats. They stretch from small herbaceous plants through shrubs and climbers to large tropical trees. Some exhibit sleep movement (closing up at night) like our native Clover, whilst others take it a step further closing on touch like the sensitive plant Mimosa.
Fabaceae has previously been known as the Leguminosae (legume family – referring to the pods they all carry) and contains the former, much more prosaic Papilionaceae (referring to the butterfly like flower form).
What ties many of the Genera within the Fabaceae together is the unique assymetric (papilionaceous) form that the flowers take. Each individual flower exhibits bilateral symmetry with 5 petals. The large upper petal is known as the banner or standard. Below this are two wings which in their turn surround two more fused petals known as the keel. Within the boat like keel are enclosed the male parts of the flower – the stamens.