Prickly comfrey or Rough comfrey [Symphytum asperum Lepechin][SYMAS][CDFA list: B] Photographs

common comfrey [Symphytum officinale L.][SYMOF]

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GENERAL DESCRIPTION:Coarse, clumped perennial herbs, typically to 1 m tall, with deep taproots and coiled inflorescences. Once established, plants are difficult to remove because small pieces of broken roots generate new plants. Roots and leaves of both species contain small amounts of toxic pyrrolizidine alkaloids that can cause liver damage when consumed in sufficient quantities.

SEEDLINGS:No description available.

MATURE PLANT:Stems ascending to erect, thick, angular, hollow, usually branched, covered with rough, bristly hairs. Leaves alternate, ovate to lanceolate, mostly stalked. Upper stem leaves sometimes sessile.

ROOTS and UNDERGROUND STRUCTURES:Taproots usually branched, deep, thick, brittle, internally white, covered with a thin blackish bark, contain much mucilage. Small broken pieces can generate new plants.

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FLOWERS:May-Summer. Cymes (determinate infloresences where the terminal flower is oldest) loosely coiled, raceme-like, axillary or terminal, consist of pairs of stalked, bell-shaped tubular flowers on the upper sides of stems. Sepals fused at base, deeply lobed, covered with bristly hairs. Flower tubes 10-15 mm long, with 5 lanceolate appendages within the tube that alternate with 5 stamens. Style 1, with 1 stigma, persistent in fruit, attached to receptacle between ovary lobes. Stamens mature before ovary. Ovary superior, deeply 4-lobed. Bee pollinated.

FRUITS and SEEDS:Fruits consist of 4 nutlets (sometimes only 1-3 mature) that separate at maturity. Nutlets ovoid, attached at the base, contain 1 seed but do not open.

HABITAT:Typically grows on moist soils of open sites, waste places, fields, ditches, abandoned gardens. Plants thrive on fertile garden soils. Tolerates cold winter climates.


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PROPAGATION/PHENOLOGY:Reproduces by seed and vegetatively from root fragments. Above ground parts die back in cold winter climates.

MANAGEMENT FAVORING/DISCOURAGING SURVIVAL:Although fragmented roots can generate new plants, repeated cultivation can eliminate weedy populations, especially when timed to prevent seed production. Mowing before seed is produced can help control weedy populations.

SIMILAR SPECIES:Borage [Borago officinalis L.] is a common garden plant that sometimes escapes cultivation. Unlike common and prickly comfrey, borage is an annual and has bowl-shaped flowers, with petals fused at the base, lobes long and widely spreading, and stamens arranged to form a conspicuous cone.

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