Teucrium canadense L. - American Germander

Teucrium canadense plant

Family - Lamiaceae

Stems - To +1m tall, from horizontal rhizomes, typically simple but branching also, 4-angled, herbaceous, with dense retrorse pubescence, hollow, erect.

Teucrium canadense stem

Leaves - Opposite, decussate, petiolate. Petiole to +/-1cm, tomentose. Blade elliptic to lance-ovate or lance-oblong, serrate, +/-11cm long, +/-4cm broad, acute, pubescent below, sparse pubescent to glabrous above. Leaf tissue abruptly contracted at base and creating a slight wing on petiole to 1mm broad.

Teucrium canadense leaves

Inflorescence - Terminal spikiform arrangement of verticillasters to +30cm tall(long). Verticillasters with +/-5 flowers each. Flowers on pedicels 2mm long. Pedicels and axis tomentose. Each flower subtended by a lanceolate-attenuate bract to +/-8mm long.

Teucrium canadense inflorescence

Flowers - Corolla highly irregular, bilabiate, light pink to purplish. Corolla tube greenish, 5mm long, dense glandular pubescent and pilose at apex. Upper lip with 2 lobes erect and shaped as horn-like appendages. Lobes to 4mm long(tall). Lower lip with two lateral rounded lobes and one large cupped central lobe. Lateral lobes to 3mm long. Central lobe to 7mm long, 6mm broad, glandular externally, often with two pinkish-purple spots near base internally. Stamens 4, didynamous, well exserted from corolla, deflexed. Filaments greenish-white, 1.4cm long, pubescent near base, glabrous above. Anthers reddish-brown, .7mm broad. Style 1.5cm long, white, glabrous, exserted from between opposing pairs of stamens, down-curved. Stigma 2-lobed. Ovary of 4 nutlets. Nutlets green and glabrous in flower. Calyx bilabiate. Calyx tube to 5mm long, glandular and tomentose. Upper lip 3-lobed. Central lobe slightly deflexed, acute, 2mm long, 2.6mm broad. Lateral lobes 1.5mm long. Lower lip 2-lobed. Lobes attenuate, 3mm long. Calyx accrescent.

Teucrium canadense flowersFlowers.

Teucrium canadense flowerFlower close-up.

Flowering - June - September.

Habitat - Prairies, wet meadows, thickets, streambanks, railroads.

Origin - Native to U.S.

Other info. - This species can be found throughout Missouri. The unusual flowers of this species make it a simple to ID in the field. The flowers are also quite showy and make the plant much deserving of cultivation. Flying insects are attracted to the flowers and the large central lobe of the lower corolla lip serves as a platform for insects to land on. The two purplish spots on the lobe are like runway lights guiding the insects to the flower.
The leaves of T. canadense have a slightly fowl odor when crushed.
Some authors, including Steyermark, split the species into different varieties but they are so similar that I won't go into them here.

Photographs taken at Logan Creek, Reynolds County, MO., 6-29-03.


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