Ulmus rubra (bark)

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Ulmus rubra Muhl.   Ulmaceae  
Syn. Ulmus fulva Michx.  
Standardized common name (English): slippery elm

Botanical Voucher Specimen

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Ulmus rubra Tropicos 100123357 (S).jpg
Source: MOBOT, Tropicos.org[1]

Ulmus rubra Tropicos 100123358 (S).jpg
Source: MOBOT, Tropicos.org[2]

Organoleptic Characteristics

[Ulmus rubra (bark)] odor distinct; taste mucilaginous.

Source: United States Dispensatory (1918) [3]

Macroscopic Characteristics

The usual height of the slippery elm is from 40 to 50 feet, with a trunk about 2 1/2 feet in diameter. In open woods and fields it is spreading and irregular in growth, but in dense woods it grows tall and straight, branching some distance from the ground. The bark is very rough, even the small branches are rough, and the twigs are furnished with rough hairs. The rather large leaves, which are from 4 to 8 inches long, are supported by short, downy stalks. The small, bell-shaped flowers appear in dense clusters in early spring, before the leaves, and are followed by flattened and circular winged fruits. Each fruit consists of a single seed surrounded by a thin, winged margin, which aids in its dispersion by the wind.

Source: American Medicinal Plants of Commercial Importance (1930) [4]

The slippery elm (Ulmus fulva), is a lofty tree, fifty or sixty feet in height, with a trunk fifteen or twenty inches in diameter. The bark of the trunk is brown, that of the branches rough and whitish. The leaves are petiolate, oblong-ovate, acuminate, nearly equal at the base, unequally serrate, pubescent, and very rough on both sides. The buds, a fortnight before their development, are covered with a dense russet down. The flowers, which are apetalous, appear before the leaves, are sessile, and in clusters at the extremities of the young shoots. The clusters of flowers are surrounded by scales, which are downy like the buds. The calyx is also downy. The stamens are five, short, and of a pale rose color. The fruit is a membranaceous capsule or samara, enclosing in the middle one round seed, destitute of fringe. outer surface of a light brown or buff color with occasional dark brown patches of adhering cork, longitudinally striate and with detachable bundles of bast-fibers, and colored blackish upon the addition of a very diluted iodine T.S.; inner surface light yellowish-brown, nearly smooth and finely striate, only slightly darkened upon the addition of a very diluted iodine T.S.; fracture fibrous with projecting bast-fibers, the broken surface porous, due to the large mucilage cells. [...] The powder is very light brown.

Source: United States Dispensatory (1918) [5]


PlantaPhile - 3123.jpg
Source: PlantaPhile[6]

Microscopic Characteristics

Under the microscope [Ulmus rubra (bark) powder] shows mostly fibrous fragments, and a finely granular portion made up of small starch grains, the latter being immediately colored bluish-black upon the addition of iodine T.S.; starch grains mostly spherical or more or less polygonal, usually about 0.003 mm. in diameter, but also attaining a diameter of 0.025 mm.; bast-fibers very long, about 0.02 mm. in diameter, with rather thin, slightly lignified walls; calcium oxalate in monoclinic prisms, mostly in crystal fibers, the individual crystals from 0.01 to 0.025 mm. in diameter; fragments of large mucilage cells with adhering starch grains. Macerate 1 Gm. of powdered Elm with 40 mils of distilled water for an hour and forcibly strain; the solution is of a mucilaginous consistence.

Source: United States Dispensatory (1918) [7]

High Performance Thin Layer Chromatographic Identification

AP-LOGO-Laboratories Crop - Copy.jpg
Ulmus rubra HPTLC ID - Natural Product Reagent + PEG-> UV 365 nm

Slippery Elm (bark) (Ulmus rubra)

Lane Assignments Lanes, from left to right (Track, Volume, Sample):

  1. 3 μL Ulmus rubra-1 (bark)
  2. 3 μL Ulmus rubra-2 (bark)
  3. 3 μL Ulmus rubra-3 (bark)
  4. 3 μL Ulmus rubra-4 (bark)
  5. 3 μL Ulmus rubra-4 (bark)
  6. 3 μL Ulmus rubra-5 (bark)
  7. 3 μL Ulmus rubra-6 (bark)
  8. 1 μL Rutin, Caffeic acid, Hyperoside, Chlorogenic Acid ~0.1% in CH3OH

Reference materials used here have been authenticated by macroscopic, microscopic &/or TLC studies according to the reference source cited below held at Alkemists Laboratories, Costa Mesa, CA. 

Stationary Phase Silica gel 60, F254, 10 x 10 cm HPTLC plates 

Mobile Phase ethyl acetate: glacial acetic acid: formic acid: water [10/1.1/1.1/2.4] 

Sample Preparation Method 0.3 g + 3 ml CH3OH sonicate/heat @ 50° C ~ 1 hr. 

Detection Method Natural Product Reagent + PEG-> UV 365 nm 

Reference see British Herbal Pharmacopoeia, 1996

Source: Elan M. Sudberg, Alkemist Laboratories [8]

Supplementary Information


  1. MOBOT, Tropicos.org http://www.tropicos.org/Image/100123357
  2. MOBOT, Tropicos.org http://www.tropicos.org/Image/100123358
  3. United States Dispensatory (1918)
  4. American Medicinal Plants of Commercial Importance (1930)
  5. United States Dispensatory (1918)
  6. PlantaPhile http://plantaphile.com/
  7. United States Dispensatory (1918)
  8. Elan M. Sudberg, Alkemist Laboratories http://www.alkemist.com
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