Thalictrum species

The Meadowrues

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The natural history of the northwoods

Name:

• Thalictrum, from the Greek, qaliktron (thaliktron), name for the European meadowrue Thalictrum minus.
• Common Name from the habitat of some Thalictrum and rue, from the Anglo-Saxon rúde, and the Peloponnesian Greek `ruth (hrute), a name originally given to Ruta graveolens and later applied to a host of plants with bitter leaves.
• Other common names include Pigamon (Qué)

Taxonomy:

• Kingdom Plantae, the Plants
  • Division Magnoliophyta, the Angiosperms (flowering plants)
    • Class Magnoliopsida, the Dicotyledons 
    • Subclass Magnoliidae
      • Order Ranunculales, the Buttercups
        • Family Ranunculaceae, the Buttercups, with Actaea, the Baneberries, Clematis, Coptis (Gold Thread), Delphinium (Larkspurs), Hepatica, Ranunculus (Buttercups), and Thalictrum (Meadow Rues).
          • Genus Thalictrum, the Meadowrues; about 100 species of perennial herbaceous plants, from the North Temperate Zone, South America, and Africa.
• Taxonomic Serial Number: 18658
• Also known as

Description:

• A ¼, ½, ¾, º,
• Herbs , perennial, from woody rhizomes, caudices, or tuberous roots.
• Leaves basal and cauline, proximal leaves petiolate, distal leaves sessile; cauline leaves alternate. Leaf blade 1-4×-ternately or -pinnately compound; leaflets cordate-reniform, obovate, lanceolate, or linear, sometimes 3-lobed or more, margins entire or crenate.
• Stem
• Flowers Inflorescences terminal, sometimes also axillary, (1-)2-200-flowered panicles, racemes, corymbs, umbels, or flowers solitary, to 41 cm; involucres absent or present, involucral bracts 2-3 (these compound, often resembling whorl of 6-9 simple bracts), leaflike, not closely subtending flowers. Flowers radially symmetric; wind-pollination
• Sepals not persistent in fruit, 4-10, whitish to greenish yellow or purplish, plane, lanceolate to reniform or spatulate, 1-18 mm;
• Petals absent
• Stamens stamens 7-30; filaments filiform to clavate or distally dilated; staminodes absent between stamens and pistils;
• Pistils 1-16, simple; ovule 1 per pistil; style present or absent.
• Fruit achenes, usually aggregate, sessile or stipitate, ovoid to obovoid, falcate, or discoid, sides prominently veined or ribbed; beak present or absent, terminal, straight to coiled, 0-4 mm. x = 7.
• Seed

  Characters useful in identifying species of Thalictrum include leaflet shape, degree of dilation of filaments, anther length, shape of anther apex, achene shape and venation patterns, and vestiture (glands and/or hairs) of leaves and achenes. Leaflets described in this treatment are the central, distalmost of a midstem leaf; proximal and distal leaves are more variable and often not representative of the species. Stigma and filament colors refer to fresh material in the following descriptions.

  Several species of Thalictrum are used as ornamentals. At least one species, T . aquilegiifolium Linnaeus, occasionally escapes cultivation in Ontario and Quebec and possibly elsewhere. The plant is tall (40-100 cm); flowers bisexual, mauve to pink; and achenes few, filiform, 3-winged, stipitate, very small, and hidden at anthesis among the bases of long, rigid stamens.

  Numerous alkaloids have been identified from plants of the genus, some with pharmacologic potential. Some exhibit antimicrobial activity; others inhibit growth of tumors or lower blood pressure in mammals.

  Species 120-200 (22 in the flora): nearly worldwide, mostly temperate.

Identification:

• Identifiable as
• Distinguished from
• The staminate plants (T. dasycarum) can be quite showy in flower but the pistillate plants are often overlooked. This species and another, T. revolutum DC., can be very difficult to distinguish from one another. A third species, T. diocum L., is easier to distinguish because it blooms in the spring and has middle and uper leaves which are long petiolate instead of sessile.
• Field Marks

North Country Meadowrue Identification

• Our four meadowrue species fall into one of two sorts:
  • small plants with multi-lobed leaflets and colorful floral filaments
  • large plants with three or fewer lobes and usually white filaments
• If you have a mature plant, under 30" in height, with leaflets divided into 3-12 lobes, look at how the compound leaves are attached to the stem.
  • If the leaves are attached by a long, single leafstalk (petiole) then you have Early Meadowrue (Thalictrum dioicum). Confirm by:
    • stem 20"-30" tall (Veiny Meadowrue is under 20")
    • achenes which, if present, are uncurved
    • largest leaflets more than 15 mm wide
    • this species has been collected from St. Louis and Lake counties in our area but not from Cook.
  • If the leaves have little or no petiole, appearing as if the first three leaf divisions all originate from the same point on the stem, then you have Veiny Meadowrue (Thalictrum venulosum). Confirm by
    • stem less than 20" tall (Early Meadowrue can be as much as 30" tall)
    • achenes which, if present, are curved
• If you have a mature plant from 2½'-6½' tall, with leaflets of three or fewer lobes, look at the shape of the leaflets.
  • If the leaflets are elongated, with at least some of them 2½ to 5½ times as long as they are wide, then you have Waxyleaf Meadowrue (Thalictrum revolutum).
  • If the leaflets are only 1 to 2½ times as long as wide, then you have Tall Meadowrue (Thalictrum dasycarpum), our most common species.
  • These two species show much overlap in characteristics and are often difficult to distinguish in the field.
    • Tall Meadowrue tends to be taller (can exceed 5')
    • Tall Meadowrue often has a purple stem (and is often known as Purple Meadowrue)
  • Waxy Meadowrue has a more limited distribution in our area having been collected from St. Louis and Lake counties but not from Cook.

Distribution:

Habitat:

Fire:

Associates:

History:

Uses:

Reproduction:

• Sexually by seed
• Flowers
• Assexually by

Propagation:

• By rhizome division,

Cultivation:

• Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
• Cultural Requirements
• Light:
• Soil:
• Water:
• Spacing:
• Fertilization:
• Size 12"-18"W x 12"-18"H
• Growth rate
• Good for
• Cultivars include
• variety 'Alba', with
• Cultivars and species available by mail order from specialty suppliers or at local nurseries

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