Cypripedium parviflorum var. pubescens (Large Yellow Lady's Slipper) - photos and description
15 cm ruler
General: Leafy plants with an upright growth habit, often found in clumps of many stems. Plants pubescent.
Flowers: Flowers solitary on long peduncles, showy, yellow, large pouch-like lower lip. Two lateral, twisted petals, greenish in colour (paler than Small Yellow Lady’s Slipper). The dorsal sepal grows above the lip, and two sepals under the lip are united together.
Slippers more than 30 mm long. Twice I’ve measured the slippers of Large
Yellow slippers, once near La Ronge, and once near Hudson Bay, both
times the slippers were very large - 45 mm long.
Leaves: Leaves are alternate, oval, we measured a leaf to 12 cm long and 5 cm wide.
Height: Height listed in Budd's Flora to 40 cm, we measured plants to 48 cm tall.
Habitat: Moist woodlands and meadows in the parklands and boreal forest.
Abundance: Large Yellow Lady's Slipper is very rare in Saskatchewan, ranked as an S2 (as of 2021) by the Saskatchewan Conservation Data Centre.
Origin: Native.
Similar plants: Distinguished from Small Yellow Lady's Slipper (Cypripedium parviflorum var. makasin) chiefly by the size of the lower lip, which in Large Yellow Lady's Slipper is > 35 mm in length, and less than 35 mm for Small Yellow Lady's Slipper. Plants in above photo had their lower lip measuring up to 45 mm. The lateral petals in Large Yellow Lady's Slipper in general are lighter in colour, yellowish-green streaked with brown, and not the dark brown colour usually found in Small Yellow Lady's Slipper.
When and where photographed: Photos taken June 28th, in swampy black spruce woods, near La Ronge, about 600 km north of Regina, SK, and July 6th wet black spruce woods Hudson Bay district, about 425 km north east of our home in Regina, SK.