tall white lettuce (TVA, White's Creek Small Wild Area, Plants)

tall white lettuce

Nabalus altissimus

Barcode data: prenanthes altissima ⁵

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Comments ⁶

Prenanthes altissima is recognized by its narrow involucres with 5 pale green, glabrous phyllaries, (4–)5(–6) florets, and pale yellow to greenish yellow corollas. Pappi in this species are most commonly whitish or pale yellow. Specimens with reddish brown to orange pappi have been recognized as var. cinnamomea, found in Arkansas, Louisiana, and Missouri. Specimens with densely hairy stems and pale yellow pappi have been recognized as var. hispidula, found mostly in New York, New England, and adjacent Canada.

Description ⁷

This native perennial wildflower is 2-6' tall and usually unbranched, except toward the apex where the flowerheads occur. The glabrous central stem is light green to purple. The alternate leaves are up to 8" long and 6" across (excluding the petioles), becoming gradually smaller as they ascend the central stem. They are quite variable in shape; the lower leaves are often divided palmately into 3 lobes (or less often 5 lobes), while the upper leaves often lack lobes (ovate or deltoid). The margins of the leaves are undulate, dentate, or entire (smooth). The upper surface of each leaf is medium to dark green and hairless, becoming yellowish green with age. The petioles are as long as the leaf blades or somewhat shorter. The foliage of this plant contains a white latex. The central stem terminates in a panicle of flowerheads that is about as wide as it is tall; smaller panicles often develop from the axils of the upper leaves. The typical panicle will have 2-4 widely spreading branches at the apex of a central stalk (peduncle); from each of these branches, several flowerheads and their buds hang downward from shorter branches (pedicels). These branches are hairless or slightly pubescent and light green to pale purple. Each flowerhead is up to ¾" long and ½" across when it is fully open; it has 5-6 outer ray florets and no disk florets. The ray florets are greenish white, cream-colored, or greenish yellow. The cylindrical base of each flowerhead has about 5 primary bracts (phyllaries) that are light green and hairless; each of these bracts is linear in shape and about ½" in length. At the very bottom of each flowerhead, there are also several secondary bracts that are much shorter than the primary bracts. The blooming period occurs from late summer into the fall and lasts about a month. Each ray floret is replaced by an achene with a small tuft of hair; these hairs are either light tan (var. altissima) or orange-brown (var. cinnamomea). The achenes are distributed by the wind. The root system is tuberous. Sometimes this species forms small colonies of plants. Cultivation

Faunal associations ⁸

Information about floral-faunal relationships for this species is limited. Bumblebees suck nectar from the flowerheads and cross-pollinate them; Halictid bees, beetles, and other insects may feed on the pollen, but they are not effective pollinators. Even though it has a bitter taste, White-Tailed Deer occasionally browse on the foliage.

Sources and Credits

(c) Suzanne Cadwell, some rights reserved (CC BY-NC), http://www.flickr.com/photos/scadwell/8732716260/
(c) Susan Elliott, some rights reserved (CC BY-NC), uploaded by Susan Elliott
(c) Rob Curtis, some rights reserved (CC BY-NC-SA), uploaded by Rob Curtis
(c) "<a href=""http://www.knps.org"">Kentucky Native Plant Society</a>. Scanned by <a href=""http://www.omnitekinc.com/"">Omnitek Inc</a>.", some rights reserved (CC BY-NC-SA), http://plants.usda.gov/java/largeImage?imageID=naal3_001_avd.tif
(c) Barcode of Life Data Systems, some rights reserved (CC BY), http://eol.org/data_objects/30667309
(c) Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/19791825
(c) John Hilty, some rights reserved (CC BY-NC), http://eol.org/data_objects/29445584
(c) John Hilty, some rights reserved (CC BY-NC), http://eol.org/data_objects/29445587

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