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Adiantum mariesii


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Family Pteridaceae

Genera ca. 40, species ca. 1000 (13 genera, 90 sp: worldwide.

Considerable disagreement exists concerning the circumscription and proper name of this family . The taxa comprising the Pteridaceae in this treatment were assigned to the Sinopteridaceae and Pteridaceae by D. B . Lellinger (1985) and were included in five families by R. E. G. Pichi-Sermolli (1977). The broad concept followed here is similar (except for the exclusion of Ceratopteris ) to that espoused by R. M. Tryon and A. F. Tryon (1982), who applied the name Pteridaceae to the group. Until very recently, the newer name Adiantaceae was more commonly used.

As represented in North America, Pteridaceae comprise three major evolutionary lines (the adiantoids, the pteroids, and the cheilanthoids). Characteristics holding the family together include abaxial (usually submarginal ) sori that lack indusia or are protected by a reflexed or revolute leaf margin , spores that are usually globose-tetrahedral and trilete, and chromosome base numbers of 30 or 29 (rarely 27). The xeric-adapted members of the family (particularly the cheilanthoids) have undergone extensive parallel and convergent evolution, and they have frustrated attempts to produce a natural generic classification based on macromorphologic characteristics alone. Although some workers have aggregated species into a few large genera (e.g. , J. T. Mickel 1979b), most tend to recognize smaller segregate genera based on a combination of morphologic, chromosomal, and biochemical data. The latter approach seems to provide a more useful, evolutionarily informative classification and is the one adopted here. Aspidotis and Notholaena are maintained here as distinct from Cheilanthes, and three recently described genera ( Argyrochosma, Astrolepis, and Pentagramma ) have been incorporated into the treatment. The reasons for these changes in generic circumscription are discussed under the individual genera.[1]

Genus Adiantum

Plants terrestrial or on rock. Stems short- to long-creeping or suberect, branched; scales deep tawny yellow to dark reddish brown [black], concolored or bicolored , linear-lanceolate to lanceolate, margins entire, erose-ciliate, or minutely dentate . Leaves monomorphic to somewhat dimorphic , densely clustered to closely spaced [distant ], 15--110 cm. Petiole chestnut brown to dark purple or blackish, with single groove adaxially, glabrous , hispid , or strigose , with 1 or 2 vascular bundles . Blade lanceolate, ovate , trowel-shaped, or fan-shaped, 1--4(--9) -pinnate proximally, membranaceous to papery , both surfaces commonly glabrous (2 species with scattered hairs ), adaxially dull or shiny, not striate ; rachis straight or flexuous . Ultimate segments subsessile to short-stalked (stalks terminating in cupulelike swelling at base of pinna in A. tenerum ), round , fan-shaped, rhombic , or oblong , 3--29 mm wide; base truncate to cuneate, free from costa; stalk dark, often lustrous ; fertile segments with marginal lobes recurved to form false indusia. Veins of ultimate segments conspicuous , free, ± dichotomously forking near base and well above segment base [anastomosing in a few tropical species], parallel distally. False indusia light gray-green or brown to dark brown, narrow, 0.6--1 mm wide, marginal, concealing sporangia until sporangia dehisce. Sporangia submarginal, borne along or sometimes also between veins on abaxial surface of false indusium, paraphyses and glands absent. Spores yellow or yellowish brown, tetrahedral-globose, trilete, rugulate to rugose or tuberculate , equatorial ridge absent. x = 29, 30.

Species ca. 150--200: nearly worldwide except at latitudes greater than 60°.

Most diverse in Andean South America, Adiantum is primarily a tropical genus; of the nine species occurring in the flora , A. melanoleucum, A. tenerum, and A. tricholepis are strictly subtropical . Adiantum hispidulum occurs only as an escape from cultivation. The genus is absent from dry areas in the interior of the continent.

Adiantum is a very clearly circumscribed genus of ferns, the character state "sporangia borne on abaxial surface of false indusium" being both necessary and sufficient to define it. Within this large and widespread genus, however, species relationships are mostly unknown. An evolutionary classification of the group is indeed much needed (R. M. Tryon and A. F. Tryon 1982).[2]


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Publishing author : Baker Publication : Gard. Chron. n.s., 16: 494 1880

Similar Species

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Members of the genus Adiantum

ZipcodeZoo has pages for 61 species, subspecies, varieties, forms, and cultivars in this genus:

A. aethiopicum (Common Maidenhair Fern) · A. aleuticum (Aleutian Maidenhair) · A. aleuticum subpumilum (Dwarf Coastal Maidenhair Fern) · A. anceps (Double Edge Maidenhair) · A. bellum (Bermuda Maidenhair Fern) · A. capillus (Common Maidenhair) · A. capillus-junonis (Junos Hair Fern) · A. capillus-veneris (Common Maidenhair Fern) · A. capillus-veneris L. 'Fimbriatum' (Fimbriatum Southern Maidenhair Fern Adiantum Capillus-Veneris) · A. capillus-veneris 'Imbricatum' (Imbricatum Southern Maidenhair Fern Adiantum Capillus-Veneris) · A. caudatum (Angel Wings) · A. caudatum 'Coll. #tlc-008' (Walking Maidenhair Fern) · A. chilense (Maidenhair Fern) · A. concinnum (Polished Maidenhair) · A. cunninghamii (Cunningham's Maidenhair) · A. diaphanum (Small Maidenhair) · A. formosum (Black Stem Maidenhair) · A. fragile (Fragile Maidenhair) · A. fragile var. fragile (Fragile Maidenhair) · A. fragile var. rigidulum (Fragile Maidenhair) · A. hirsutum (Hairy Maidenhair) · A. hispidulum (Rosy Australian Maidenhair Fern) · A. hispidulum 'Bronze Venus' (Rough Maidenhair) · A. jordanii (California Maidenhair) · A. latifolium (Broadleaf Maidenhair) · A. lunulatum (Crescent Maidenhair) · A. macrophyllum (Large-Leaf Maidenhair-Fern) · A. melanoleucum (Fragrant Maidenhair) · A. obliquum (Oblique Maidenhair) · A. pedatum (American Maidenhair Fern) · A. pedatum subpumilum (Maidenfern) · A. pedatum 'Eco Aurora-Borealis' (Eco Aurora-Borealis Northern Maidenhair Fern Adiantum Pedatum) · A. peruvianum (Peruvian Maidenhair Fern) · A. petiolatum (Stalked Maidenhair) · A. philippense (Philippine Maidenhair) · A. pulverulentum (Glossy Maidenhair) · A. pyramidale (Pyramid Maidenhair) · A. raddianum (Delta Maiden-Hair Fern) · A. raddianum 'Bridal Veil' (Bridal Veil Delta Maidenhair Fern Adiantum Raddianum) · A. raddianum 'Crested Fritz' (Maidenhair Fern) · A. raddianum 'Fritz-Luthi' (Fritz-Luthi Delta Maidenhair Fern) · A. raddianum 'Gracillimum' (Maidenhair Fern) · A. raddianum 'Micropinnulum' (Micropinnulum Delta Maidenhair Fern Adiantum Raddianum) · A. raddianum 'Ocean Spray' (Maidenhair Fern) · A. raddianum 'Pacific Maid' (Pacific Maid Delta Maidenhair Fern) · A. raddianum 'Sleeping Beauty' (Maidenhair Fern) · A. raddianum 'Variegatum' (Variegatum Delta Maidenhair Fern Adiantum Raddianum) · A. radiatum (Delta Maidenhair Fern) · A. tenerum (Black Stick Maidenhair Fern Adiantum Tenerum) · A. tenerum var. farleyense (Black Stick Maidenhair Fern) · A. tetraphyllum (Fourleaf Maidenhair) · A. thalictroides 'Argentine Lace' (Meadow-Rue Maidenhair Fern) · A. tracyi (Tracy's Maidenhair) · A. trapeziforme (Diamond Maidenhair) · A. tricholepis (Deer Maidenhair-Fern) · A. venustum (Evergreen Maidenhair Fern) · A. villosum (Woolly Maidenhair) · A. viridimontanum (Green Mountain Maidenhair) · A. vivesii (Puerto Rico Maidenhair) · A. wilsonii (Wilson's Maidenhair) · A. x tracyi (Tracy's Maidenhair)

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Further Reading

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  1. Michael D. Windham "Pteridaceae". in Flora of North America Vol. 2. Oxford University Press. Online at [back]
  2. Cathy A. Paris "Adiantum". in Flora of North America Vol. 2. Oxford University Press. Online at [back]
Last Revised: 2/1/2015