Note that the key to the species in Flora of Alberta requires:

leaves usually more than 10 mm wide.

In fact, only the lower leaves are more than 10 mm wide; the upper ones are narrower.

Note that some taxonomists place the Lobelia genus in the Campanulaceae family.

 

Spicata:  Answers to key questions in Budd's Flora and Flora of Alberta leading to this species.   plants terrestrial; NOT [plants aquatic, with leaves all submerged] plants of drier soils; NOT [plants of moist marshy places] stems leafy; NOT [leaves all basal] stem leaves lanceolate to oblanceolate to ovate, usually more than 10 mm wide; NOT [stem leaves linear, less than 10 mm wide] flowers in a spike-like raceme; NOT [flowers in a loose raceme, on lax pedicels] racemes many-flowered; NOT [racemes few-flowered]

Lobelia: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus.  perennials; NOT annuals corolla-tube split to near the base on the upper side capsule 2-celled; NOT 1-celled

 

Lobeliaceae: Answers to key questions in Budd's Flora leading to this family.  herbs plants green or with some chlorophyll; NOT [plants parasitic or saprophytic, without chlorophyll] plants often with milky juice; NOT [plants without milky juice] NOT climbing plants with tendrils leaves basal or alternate; NOT [leaves opposite] flowers NOT in heads, NOT in spikes flowers with two floral rings, but with the petals wholly or partly united forming a tube or bell corolla irregular, split down one side; NOT [corolla regular, bell-shaped] anthers united into a tube; NOT [anthers free] ovary inferior; NOT superior