PRIMULACEAE. 191 



279. TRIENTALIS. Star-flower. 



Low smooth perennials, with simple erect stems; leaves few, 

 alternate, minute and scale-like, except a whorl of thin veiny- 

 leaves at the summit of the stem ; corolla spreading, flat, without 

 a tube; filaments slender, united at the base; anthers oblong, 

 revolute after dehiscing; capsule few-seeded. 



Trientalis latifolia Hook. Stems 10-30 cm. high, from small rather deep- 

 seated tubers; leaves 4-7, whorled near the top, lanceolate to oblong-oval, 

 acute, 3-8 cm. long, short-petioled; pedicels very slender, shorter than the 

 leaves; petals pink, lanceolate, acuminate. In woods, Blue Mountains. 



280. NAUMBURGIA. 



Erect perennial leafy herbs with slender rootstocks; leaves 

 opposite, sessile, punctate; flowers in axillary spikes; calyx 5-7- 

 divided, the segments linear; corolla deeply 5-7-parted, the tube 

 very short and the segments narrow; stamens 5-7, exserted; 

 filaments slender, slightly united at the base; capsule 5-7-valved, 

 few-seeded. 



Naumburgia thyrsiflora (L.) Duby. Glabrous or nearly so; stems simple' 

 20-60 cm. high, erect, from creeping rootstocks; leaves lanceolate, sessile' 

 3-5 cm. long, the lower ones reduced and scale-like; peduncles axillary from 

 the 1-4 middle pairs of leaves; flowers small, in a dense oblong spike, pale 

 yellow; calyx-lobes linear-lanceolate, acute; capsule glandular-dotted. In 

 wet places, Rock Lake; banks of Spokane River at Spokane; Mud Lake, Koo- 

 tenai County, Idaho. 



281. CENTUNCULUS. 



Small annuals with leafy stems; leaves entire; flowers small, 

 inconspicuous, sessile or nearly so, solitary axillary; corolla 

 rotate, with a short tube, usually withering on the summit of 

 the pod ; stamens 4 or 5 ; filaments beardless. 



Centunculus minimus L. Glabrous; stems slender, 5-20 cm. high; leaves 

 ovate to obovate, narrowed at base, 4-6 mm. long; flowers axillary, sessile 

 or nearly so, the parts mostly in fours, sometimes in fives; calyx-lobes lanceo- 

 late-subulate. In low wet places, Spokane County, and adjacent Idaho. 



282. STEIRONEMA. 



Leafy-stemmed perennials; leaves all opposite but seemingly in 

 whorls on the flowering branches; flowers yellow, on slender 

 axillary peduncles; calyx 5-parted; corolla rotate, deeply 5- 

 parted; capsules 10-20-seeded. 



Steironema ciliatum (L.) Raf. Stems erect, usually simple, 30-90 cm. 

 high, puberulent above or wholly glabrous; leaves opposite, or the upper 

 whorled, ovate, acuminate, rounded or cordate at base, the margin ciliate, 

 2-4 cm. long; petioles broad, coarsely ciliate, 1-2 cm. long; pedicels exceeding 

 the leaves; flowers yellow, 1.5-2 cm. broad; calyx-lobes lanceolate, acuminate, 

 shorter than the petals. Along streams and ponds, common. 



