Re: fern breeding
- Subject: Re: [ferns] fern breeding
- From: "Tom Stuart" email@example.com
- Date: Thu, 06 Jan 2005 18:31:45 -0500
- Content-description: Mail message body
A few years ago on the Alpine-L list a member asked, "When you encounter a new
plant, how do you tell whether it's a perennial or an annual?"
That list has over a thousand members. There was no answer. Maybe some thought
it was a dumb question, but the more I rolled it around, the more complicated
the answer seemed. By a long measure, it was the most interesting unanswered
question of the year.
Two weeks ago here Tony Avent asked,
> does anyone know of a list of apogamous ferns...especially winter hardy ones?
Yes, this is also an interesting question, even though it isn't about
It is interesting horticulturally because apogamy guarantees the fern comes
true to form, the offspring of a cultivar being precisely that cultivar.
Moreover, apogamous ferns, bypassing the sexual phase, produce new sporophytes
Taxonomically, the question is of interest because apogamy poses a number of
riddles. How does apogamy coexist with evolution? Why are some genera loaded
with apogamous species, others not at all? Sometimes loaded genera are
phyletically far removed from each other, so did this set of characteristics
arise many times in evolution?
As an aside, apogamy requires two separate events. First the normal meiotic
division in the sporangium is corrupted (two paths are known), producing 2n
chromosomes in the spores instead of n chromosomes. Second, the spore
germinates and the resulting gamete independently produces a sporeling without
any fertilization or concurrent recombination.
Cyrtomium is largely, not entirely, apogamous. Did this arise once or many
times? If once, how did new species evolve? If many times, is apogamy a dead-
Why is apogamy relatively common among Japanese ferns (estimated at 13%) while
in New Zealand it is much less common (2-3% of species)?
Its high incidence among some cheilanthoids (Cheilanthes, Pellaea, Astrolepis)
is theorized to have an advantage in desert climates due to rapid establishment
of the new plant after a rainfall. What is the advantage in woodlands?
The list below is preliminary. Partly this comes from a choice to start with
the genera reflected in the temperate flora -- though not restricted to just
the temperate species. Partly it is the lack of experimental data in much of
the world (North America, Europe, Japan, New Zealand, Sri Lanka floras are well
represented, other areas not). Australian ferns have been examined, but I do
not have access to the results. Perhaps someone here has a key to:
Another digression. Apogamy can be induced by chemical means or by the stress
of preventing fertilization. Can someone enlighten us as to whether these
means are strictly exploratory or already have practical application? In any
case I strove to exclude such reports.
The marking 'both' in the list below means the species reproduces both by
apogamy and sexual means. The two methods are sometimes reflected in separate
subtaxa, sometimes by geographical origin, or the cytology may not be reflected
in either morphological or geographical differences; the reference (see below)
may have the details. An absence of 'both' only means no test has yet confirmed
The first list of apogamous ferns was produced by the mother of cytology, Irene
Manton, in 1950. An update:
First, temperate genera with no demonstrated apogamy:
Arachniodes, Aspidotis, Athyrium, Blechnum, Cryptogramma, Cystopteris,
Dennstaedtia, Deparia, Gymnocarpium, Lygodium, Matteuccia, Onoclea, Oreopteris,
Osmunda, Pentagramma, Pityrogramma, Pleopeltis, Pteridium, Pyrrosia, Woodsia,
Genera where apogamy is rare or singular contain these species:
Adiantum caudatum (both), hispidulum, philippense
Ophioglossum coriaceum (both)
Phegopteris connectilis (both)
Polypodium scouleri (both)
Thelypteris glanduligera and parasitica
Genera where the incidence is moderate or high:
Asplenium aethiopicum, apogamum, cheilosorum (both), cataractarum,
Asplenium filipes (both), hondoense (both), mertensianum, A . monanthes
Asplenium resiliens, and A. W heteroresiliens
Astrolepis cochiensis (both), crassifolia, integerrima, sinuata (both)
Cheilanthes alabamensis, arizonica, bonariensis, eatonii, feei
Cheilanthes farinosa (both), kaulfussii, lindheimeri, sieberi, tomentosa
Cheilanthes villosa, wootonii
Cyrtomium caryotideum, falcatum (both), fortunei, macrophyllum
Diplazium dilatatum var.dilatatum (both) and var. heterolepia
Diplazium hachijoense, kawakamii var. kawakamii, doederleinii, donianum
Diplazium procumbens, simplicivenium
Diplazium virescens var. virescens, var. conterminum, var. okinawaense, and two
other unnamed varieties
Diplazium taiwanense, D.Wkawabatae, D.Wtakii, and D.Wnakamurae
Dryopteris acutodentata, affinis (both), basisora, blanfordii, bissetiana
Dryopteris championii (both), chinensis, cycadina, cystolepidota, decipiens,
Dryopteris dickinsii, erythrosora, formosana, fuscipes, gymnosora
Dryopteris hadanoi, hakonecola, hondoensis, indusiata, integriloba
Dryopteris juxtaposita, khullarii, kuratae, lepidopoda (both)
Dryopteris namegatae, neorosthorni, odontoloma, pacifica, parrisiae
Dryopteris purpurella, pseudo-filix-mas, pycnopteroides, remota, ryo-itoana
Dryopteris sacrosancta, shibipedis, silvaticum, simasakii, sparsa (both)
Dryopteris stewartii, subbipinnata, sublacera, subtriangularis
Dryopteris tsugiwoi, tsutsuiana, varia, wallichiana (both), yakusilvicola
Notholaena aliena, N. aschenborniana, N. californica (both), N. grayi, N.
Pellaea andromedifolia (both), P. atropurpurea, P. boivini, gastonyi
Pellaea glabella (both), intermedia (both), lyngholmii, ovata (both)
Polystichum kiusiuense, luctuosum (both), monticola, neolobatum
Polystichum rigens, tsus-simense, xiphophyllum
(most of Polystichum is tropical montane, most untested, fertile ground)
Pteris biaurita, cretica, cadieri, excelsa, esquirolii, fauriei (both)
Pteris grevilleana, kiuschiuensis, linearis, natiensis, setuloso-costulata
A majority of references for these taxa can be found on the web. For a copy of
the list write to me privately. And, of course, please add to or correct the
above, publicly or privately.
Yes, an interesting question.
Tom Stuart, New York
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