Aquatic and Wetland Vascular Plants of the Northern Great Plains

Physostegia Benth. -- Obedient plant

Stout, erect, perennial herbs; stems arising singly from slender rhizomes or from a slender caudex, simple throughout or branched at the base of the inflorescence. Leaves sessile or the lowermost sometimes short-petioled, elliptic to lanceolate or oblanceolate, mostly serrate. Flowers showy, pinkish-lavender to purple-lavender, short-pedicelled and borne singly in the axils of short bracts, arranged in 1-several terminal and lateral, spikelike racemes. Calyx regular or nearly so, tubular-campanulate, 5-toothed, the teeth much shorter than the tube; corolla bilabiate, much longer than the calyx, the upper lip hoodlike, entire to emarginate, the lower lip about equaling or shorter than the upper, shallowly 3-lobed; stamens 4, included or slightly exserted under the upper corolla lip; stigma 2-lobed, style about equaling the stamens. Nutlets ovoid, unequally trigonous, smooth.

References:  

Cantino, P. D.  1981.  Change of status for Physostegia virginiana 
     var. ledinghamii (Labiatae) and evidence for a hybrid 
     origin.  Rhodora 	83:111-118. 

Lundell, C. L.  1959.  Studies in Physostegia I.  New species and 	
     observations on others.  Wrightia 2:4-12.

Lead	Characteristic	Go To
1	Upper leaves clasping the stem, some of them usually broadest near the base of the blade; corolla usually with some stipitate glands (often lacking in P. ledinghamii); rare species in our area.	Lead 2
1	Upper leaves not clasping the stem, broadest at the middle or above; corolla glabrous or sparsely puberulent but lacking stipitate glands; common species.	P. virginiana
2	Corolla 14-23 mm long, often lacking stipitate glands; nutlets 2.8-4 mm long.	P. ledinghamii
2	Corolla 9-16 mm long, usually with stipitate glands; nutlets 2.1-3.3 mm long.	P. parviflora

41. Lamiaceae, the Mint Family

3. Physostegia Benth. -- Obedient plant

1. Physostegia ledinghammii (Boivin) Cantino

2. Physostegia parviflora Nutt. ex A. Gray

3. Physostegia virginiana (L.) Benth.

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