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divisions rather long-stalked, tripinnate ; the terminal larger, some-
times quadripinnatifid below ; ultimate segments oval or rarely
lobed and slightly narrowed below, the margins entire, the rachises
broadly winged, the surfaces bluish glaucous : sporophylls 20-
35 cm. or more long on stout stalks, 'the panicles 6-12 cm. or
more long, quadripinnate.

Mexico : *' In montibus prope San Luis Potosi," Oct. 1879,
Schaffner, U (type) K ; San Miquelito Gebirge (San Luis Potosi),
Schaffner^ -^5, C (numerous specimens); Valle de Mexico, 1875,
Schaffner, B.

The plant is considerably smaller, more fleshy and glaucous
than B. decompositum and is correspondingly more compact in
growth and has usually shorter petioles. It is much more finely
divided than either that species or B. obliquum to which it is some-
what related. I take pleasure in naming the species after its sole
collector, Dr. Schaffner, who sent me fine specimens over twenty
years ago, shortly before his death.
Botrychium silaifolium Presl. Rel. Haenk. i: 76. 1825. —

California and northward.
Botrychium Silesiacum Kirschlg. Fl. Alsac. 401. 1855. Not.

known and description not seen.
Botrychium simplex Hitchc. Am. Jour. Sci. 6 : 103. //. 8, 1823.

Botrycltium KanneTibergii Klinsman, Bot. Zeitung, 10 : 378.
1852.



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Described Species of Botrychium 62

New England, New York, New Jersey, Pennsylvania, ? Wyo-
ming ; Northern Europe.

Botrychium strictum sp. nov.

A tall plant with the habit of B, Virginianum with a sessile
sterile lamina and slender spicate panicle. Roots fleshy : stems
25 cm. or more long, slender, with slightly fibrillose covering :
sterile leaf broadly triangular, sessile, of three equal or subequal
2-3 pinnatifid divisions ; primary pinnae 6-10 cm. long, strongly
decurrent on the rachis, with 8-10 pinnules on each side which
vary from oblong-lanceolate to lanceolate ; pinnules varying from
deeply 4-5-crenate to 5-cleft on each side, blunt or rounded at the
end: panicle 6-13 cm. long, on a slender stalk 5-6 cm. long,
with 16-20 short compact branches 5-15 mm. long, placed at an
acute angle with the axis, thus causing the entire panicle to appear
spike-like : sporangia much crowded, large, nearly i mm. in diam-
eter : spores pale yellow.

Japan : Sapporo in groves, Aug. 1894, A. W, Stanford (ty^
in the herbarium of the New York Botanical Garden); **in
sylvis Takaosan., prov. Musashi, 10 Oct. 1885 " comm. J. Matsa-
mura, U. I have also seen a specimen in the Museum of tht Jar-
din des Plantes at Paris, and one in the herbarium of Mr. B. D.
Gilbert. The species has hitherto been reported from Japan under
the name of B. Virginianum but it is clearly a very distinct species,
differing widely in the cutting of the leaf and in the narrow spike-
like panicle which is also much shorter than in our familiar species.
In the new species the mature panicle scarcely overtops the sterile
leaf when laid on the herbarium sheet.
Botrychium subbifoliatum Brack. U. S. Expl. Exped. 16 : 317.

//. 4.4,/. 2, 1854. — Sandwich Islands.
Botrychium subcarnosum Hook. & Grev. = B. daucifolium.
Botrychium tenebrosum A. A. Eaton, Fern Bull. 7: 8. 1899. —

New Hampshire, Vermont, Connecticut, New York.
Botrychium tenellum KngsU. Bot. Notiser, = B. ramosum {^pLjuii.),

Botrychium tenuifolium sp. nov.

A slender-stemmed species allied to B. obliguum but with the
segments thin and reduced to nine in number. Stem very slender,
2-4 cm. long, 1-1.5 mm. thick: leaf 3.5-5 cm. long, 3-6 cm.
wide, usually consisting of only nine segments (/. e., strictly biter-
nate), with the three divisions subequal ; occasionally larger forms
show a pair of additional lobes on the terminal division ; segments



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6S Underwood : Index to the

ovate, 1. 2-1 5 cm. long by 6— 8 mm. wide, thin, sharply serrate, or
in larger forms occasionally two or three times incised ; petiole
3-6.5 cm. long, very slender: panicle 3-6 cm. long, bipinnate or
rarely tripinnate below, on a slender stalk 6-22 cm. (usually
12-14 cm.) long.

Specimens have been examined as follows :

Louisiana : Alexandria, Hale (Chapman herbarium), C (type).

Florida : ** River banks," C. Communicated many years
ago to Torrey who had endorsed it : " Seems to come near B,
simplex Hitch."

Alabama : Auburn, 1895, Underwood, U ; 15 Oct. 1896, Earle,
C ; 22 Oct. 1896, C, R Baker, C ; Oct. 1897, Baker & Earle, C.

Missouri : Butler county, 4 Nov. 1892, Bush, C.

This species is nearest related to B. obliquum which it appears
to replace in the coastal plain of the gulf region. It is much more
slender than B, obliquum and the leaf is not only much less divided
in mature forms, but is also thinner and usually sharply serrate
almost as in B, Japonicum, Typical forms have only nine seg-
ments to the leaf.
BoTRYCHiUM TERNATUM (Thunb.) Sw. Schrader*s Jour. Hot. 1800* :

III. 1801.

Osmunda ternata Thunb. Fl. Jap. 329. pi* 32. 1784.

Japan, China, India.

A number of species were referred to this species as varieties by
Milde, and the practice is still followed by some of his modern
admirers. There seems to be no difference of opinion relative to
the existence of the groups of individuals as distinct groups, the
only difference appearing to be the rank that shall be assigned to
them. The ternatum group represents a closely allied group of
forms that appear to have become widely scattered from some
common center. There is no rational doubt but that they have had
a common origin ; this of course is the only possible explanation
of their structural and habital relationship. Now where was the
original center from which they sprung ? According to the system
that would make them varieties of B, ternatum because that species
happened to be the first described, it would seem to follow that that
centre was in Japan, otherwise they could not be varieties of a
Japanese species. The current system of naming varieties is a stupid



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Described Species of Botrychium 54

practice handed down to us from the past and is wholly at variance
with the modem conceptions of evolution. The original centre in
all probability was not in Japan so that the members of the teruaHim
group are not varieties sprung frpm B. tematum, and it creates %
£dse impression to continue to call them so. They are distinct
tMngs as everyone admits, and we maintain it is more rational and
more in accord with our conceptions of evolutionary origin from a
common stock to call them species. It is also much simpler and
leaves us free to determine the original centre of distribution and re-
lationship without prejudice. The practice of naming varieties on
slight environmental characters ought to cease, and botanists should
discourage the naming of such trivialities. A marked example of
how far this reduction of species to varieties can be carried is seen
in Dr. Christ's reduction of Dryopteris marginalis and D, Goldieana
to varieties of D, filix-mas. For a European who has never seen
cither of the species growing in its native habitat to take such
liberties with American species is to say the least violating the code
of international courtesy and ought to stand as a warning to those
who still hold to the ancient heresy that Europeans know more
about the American flora than we do ourselves.
Botrychium Virginianum (L.) Sw. Schrader's Jour. Bot. 1800* :

III. 1801.

Osmunda Vtrgirnana L. Sp. PI. 1064. 1753.

Botrychium gracile Pursh, Fl. Am. Sept. 2: 656. 18 14.

Botrychium anthemoides Presl, Abh. Bohm. Ges. Wiss. 5 : 323.

1847.
Botrychium Virginianum Mexicanum Hook. & Grev. Bot. Misc.

3: 222. 1833.

Botrychium brachystachys Kunze, Linnaea, 18 : 305. 1844.

Mexico. Moore referred this to B, cicutarium^ which he made
a subspecies of B, Virginianum, The species or variety appears
to be quite rare in collections although Mr. Pringle once wrote me
that it was quite common in Mexico. It is desirable that it be com-
pared in the field with more northeastern types of the species. The
region of Mexico has been widely traversed by Mr. Pringle and
others who have brought to light a large number of new species,
but they have almost as systematically neglected to collect the
old ones, and consequently our knowledge of the distribution of



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65 Underwood : Index to the

Mexican plants is still lamentably defective. The whole Mexican
region will have to be gone over piecemeal, and collections made
that will give some conceptions of the distribution of many of the
species of that prolific country. Among them is this Mexican
representative of our common rattlesnake fern of which scarcely
any specimens exist in American collections.

[The figures on page 49 illustrate four species : /. /, ^ =
Botrychium Onondagense ; /. j = Botrychium Lunaria ; /. ^, 5 =
Botrychium neglecttim ; f, 6^ y =- Botrychium tenebrosunt,']

Columbia University,
25 December 1902.



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The Publications of the Department of Botany ^ Co-
lambia University, consist of Memoirs in quarto and
Contributions in octavo.

The Memoirs already published are: —

Vol. I. Small. A Monograph of the North American Species of
the Gqtius Pofy^o^iUf /I. Pp.178. 84 plates. 1895. Price,
six dollars.

Vol. II. Rydberg. A Monograph of the North American Poten-
tilleae. .Pp.224. 112 plates. 1898. Price, six dollars.

The Contributions have now reached the ninth volume.

Vol. I. Nos. I-2S (1886-1892). Out of print, except Nos. 6, 7,
1 1, 13, 17, 20, 21, 22, 24. These can be supplied at twenty
five cents each, except No. 6, which is one dollar.

Vol. II. Nos. 26-50 (1892-1894V Nos. 26, 28. 29, 32, 33, 34, 36,
and 39 are out of print ; other numbers can be supplied at
twenty five cents each, except No. 35, which is one dollar
and a half.

Vol. III. Nos. 51-75 (1894-1895). Nos. 52, 54, 60, and 72 are
out of print ; others can be supplied at twenty five cents
each.

Vol. IV. Nos. 76-100 (1895-1896). Five dollars; single num-
' bers twenty five cents each.

Vol. V. Nos. 101-125 (1896-1897) Five dollars; single num-
bers tventy five cenls, except No. 119 which is fifty cents,
and No. loi which can only be supplied with full volumes.

Vol. VI. Nos. 126-150(1897-1898). Fivedollars. Nos. 133, 136,
146, and 150 can be had only in orders for the complete
volume; other numbers, twenty five cents, except Nos. 129
and 143, which are fifty cents each.

Vol. VII. No. 151-175 (1898-1901). Five dollars. Nos. 157 and
158* cannot be furnished separately ; other numbers twenty
five cents each.

Vol. VIII. No. 176-200 (1901-1902). Five dollars ; single num-
bers twenty five cents, except No. 176 which is fifty cents.

Vol. IX. No. 201 — (current).

* Nos 157 and 158. with the set of nine papers by Mr. BicUnell on Sisyrinchium,
can be had for one dollar and fifty cents.

Lists of titles of Contributions may be had on application.

LuciEN M. Underwood,
Columbia University, Professor of Botany,

New York city.



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CONTRIBUTIONS FKOM THE DEPARTMENT OF BOTANY
OK COLUMBIA UNIVERSITY— No. 202



STUDIES IN PLANT HYBRIDS: THE SPERMATO-
GENESIS OF HYBRID COTTON



By WILLIAM AUSTIN CANNON



NEW YORK
1903



t Kei>rlnte<l from the Bulletin op the Torkey Botanical Club. 30? 13:3-17'2. Mr m>;]J



■ - " !■



■ \ -'^" • ^ LIBRARY OF THE GRAY HERBARIUM
; HARVARD UNIVERSITY.

THE GIFT OF

i

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Studies in Plant Hybrids: The Spermatogenesis of Hybrid Cotton

By William Austin Cannon
(With Plates 7 and 8)

Introduction

Perhaps the first suggestion that we have as to the possibility of
crossing two or more less distantly related plants was given by
Camerarius * in his letter to Valentini on the sexuality of plants.
This was in the year 1694. In this letter Camerarius speculates as
to the effect of crossing the hemp {Cannabis) and the hop {Humu-
lus), wondering whether the posterity of the form used as the
mother would by this cause be altered. He did not make the
cross, and in fact it was not until 1 760 that the first plant hybrid
which was of use to science was made. In that year K61reuter,t
perhaps the greatest as he was the first of hybridizers, crossed
Nicotiana paniculata $ and N, rustica 9 and obtained fertile off-
spring, and thus began successfully the experimentation which he
carried on with so great results for several decades.

The first plant hybrid thus empirically formed served a good
purpose by providing incontestable evidence upon certain of the
leading biological questions of the day. It fortunately was of the
intermediate type, and thus the fact that both parents contributed
equally to the formation of the hybrid offspring demonstrated at
once the falsity of the evolution or preformation hypothesis, gave

* Camerarius, Ueber das Geschlecht der Pflanzen, translated from the Latin ** De
sexu piantarum epistola." (Ostwald*s Klassiker der exakten Wissenschaften, 105 : 49.

1899)

f Kdlreuter, Vorl&ufige Nachricht von einigen das Geschlecht der Pflanzen. (Ost-
wald's Klassiker der exakten Wissenschaften, 41 : 30. 1893. )

fThe preceding number of the Bulletin, Vol. 30, No. 2, for Febuary, 1903 (30:
75-132), was issued 28 F 1903,]

133



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134 Cannon: Studies in Plant Hybrids

a strong support to the idea of sex in plants, and also pointed the
way to the true conception of fertilization.

In addition Kolreuter, in the course of his long career as a
hybridizer, arrived at other results that were of almost equal im-
portance. For instance, he first pointed out the meaning of the
visits of insects to flowers, and thus formed the basis for Sprengel's
subsequent work, and he first showed the significance of nectar
in this connection.* Kolreuter also introduced the*' modem"
methods in experimental research, as a single illustration taken
from many will suffice to show. He had the mistaken idea that
the part of the pollen necessary to insure fertilization was the fluid
which he had observed about it and which he supposed originated
in the interior of the grain and oozed out through the pores. He
therefore was interested to learn how many grains were required
to effect fecundation. To ascertain this he counted the grains in
a flower and artificially pollinated with a varying but a known
number. In Hibiscus Trionum he counted 4,863 grains, and
found that only 50-60 were necessary to fructify more than 30
ovules. In Mirabilis Jalapa and M, longiflora two or three, or
only one were required to fertilize the single ovule.

Kolreuter recognized all of the important characteristics of
plant hybrids. t He learned that species-hybrids were as a rule
intermediate and uniform, whichever race provided the male or
female parent He observed the fruitfulness of variety-hybrids,
the sterility or lessened fruitfulness of those between species, the
stronger growth of many hybrids and other phenomena. In his
experiments Kolreuter used mainly the following genera : Aqui-
legia, Matthiola, Dianthus, Melandrium, Linum^ Malva, Lavatera^
Lobelia^ Nicotiana, Datura^ Lycium^ Verbascum^ Digitalis and Mira-
bilis,

About the time that Kolreuter was engaged in the experi-
mental study which gave such remarkable results, Linne, ignoring
that scientist's work, put forward theories in which hybrids played
a prominent role. And this was done with hardly any experi-
mental basis for his ideas. I refer to Linne's hypotheses regard-
ing the origin of genera and species. According to Sachs (/. r.

* Sachs, Geschichte der Botanik, 440. 1875.
fFocke, Die Pflanzen-MischliDge, 431. 1881.



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Cannon: Studies in Plant Hybrids 135

114) the doctrine is in brief this, in the first place classes were
created, by the subsequent mixing of the individuals of the differ-
ent classes genera arose, and finally by the crossing of these
genera species were differentiated.

It was not long however before some practical tests were made
of the relation of the constancy of species to the possibility of
deriving fertile hybrids by crossing them. Apparently without
an adequate reason for his belief, Sprengel thought that crosses
between distinct natural species might be fertile, and he accord-
ingly is pleased to discover means by which plants may resist
hybridizing, as for instance the difference in season of the matura-
tion of the reproductive organs. This is considered by him as a mi-
raculous adaptation for the preservation of the purity of the species.
The relation of Kolreuter's results and methods to the science
of his time is so well given by Sachs that I shall quote a paragraph
direct (/. c. 446): ** Der allgemein theoretische Werth von Koelreu-
ter's kunstlichen Pflanzenbastarden ist gar nicht hoch genug anzu-
schlagen ; die Vermischung der Eigenschaften der vaterlichen und
mutterlichen Form war der starkste Beweis gegen die Evolutions-
theorie und liess gleichzeitig einen tiefen Blick in das wahre
Wesen der sexuellen Vereinigung thun. Auch ging aus Koel-
reuter's zahlreichen Untersuchungen sofort hervor, dass nur ganz
nahe verwandte Pflanzen und auch diese nicht immer einer gesch-
lechtlichen Vereinigung fahig sind. wodurch die vagen Vorstel-
lungen Linne's fur jeden Urtheilsfahigen sofort beseitigt wurden,
wenn es auch immerhin noch lange dauerte, bis die Wissenschaft
alle Vortheile aus Koelreuter*s Untersuchungen zog. Die Pflan-
zensammler aus der Linne'schen Schule ebenso, wie die eigent-
lichen Systematiker am Ende des vorigen Jahrhunderts, hatten
kein Verstandniss fiir derartige Leistungen, ja Koelreuter's Ergeb-
nissen zum Trotz, verbreiteten sich in der botanischen Literatur
spater unrichtige Vorstellungen iiber Bastarde und ihre Fahigkeit
sich fortzupflanzen ; den Glaubigen der Constanzlehre konnten die
Bastarde ohnehin nur unbequem sein, sie storten ihnen die Rein-
lichkeit des Systems und passten zudem nicht recht zu der
Annahme, dass jede Species eine * Idee ' reprasentire.*'

Whether hybrids between parents of different species are
always sterile, and those between varieties always fertile, soon



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136 Cannon :, Studies in Plant Hybrids

became a question of great importance, since by this means it was
hoped that a distinction between varieties and species might be had.
Early in the nineteenth century the question was taken up by
English and later by French botanists and since the facts were not
well known the bearing of them on the question under discussion
was also much in dispute. In England, Herbert * and Knight f
discussed the relative fertility of species- and variety-hybrids,
the latter author holding that hybrids from parents of different
species are always sterile, but on the other hand that the varietal
hybrids are always fertile. From the results of his experiments
and study Knight concluded also that fruitful hybrids indicate
that the parents are not distinct species, but varieties of the
same species. Herbert on the contrary found that hybrids between
different species are not seldom fertile. As to the significance of
this he does not appear to think the parents were of the same
species, but rather (/. c, i6) that they **have branched out from
one common stock since the creation of the world." He further
says : ** If it be admitted, that diversity of species could have been
produced by variations of soil, temperature, or humidity, it will be
readily understood that such diversity might have been further
multiplied by hybrid intermixture, as the species were brought
together by the natural progress of their diffusion."

It will not be necessary for the purposes of this paper to enter
more into the details of this phase of the ** constancy of species "
doctrine. The ground that Knight and Herbert threshed over in
England was gone over again later (1862) in France by Naudin
and Godron.J Finally, Darwin § has pointed out that not only
is the fertility or sterility of a hybrid no criterion of the relationship
of the parents, but that the hybrid may even be more fruitful than
either pure parent.

Focke (/. c. 443) says that up to the time of Nageli (1865) the
knowledge of hybrids was unconnected and fragmentary, and that
this author united and made coherent the results of the earlier
hybridizers. Especially he drew consistent conclusions from the

* Herbert, On the Production of Hybrid Vegetables. Trans. Hort Soc. Lond. 4 :
15. 1820.

t Knight, Observations on Hybrids. Trans. Hort. Soc. Lond. 4: 367. 1821.

J Focke, Die Pflanzen-Mischlinge, 441. 1881.

J Darwin, On the Origin of Species, Am. ed., 235. 1883.



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Cannon : Studies in Plant Hybrids 137

facts gathered together by Gartner. The general conception of
hybrids held at the present is based on Nageli's writings. He
noted the tendency of hybrids to vary, and to revert, and he
showed the value of the reciprocal cross, and, finally, he formu-
lated the laws governing the action of hydrids. He also ob-
served the behavior of hybrids in the second and later genera-
tions when they were inbred, although the significance of this
was of course not appreciated by him.

At the time when the work of Nageli was being published, that
of Gregor Mendel * had been recently presented to the society at
Brunn. His main theme was to account for the behavior of hy-
brids in the second and later generations. It will not be necessary
in this place to present a full account of Mendel's laws because
since their rediscovery by de Vries,t Correns,J and Tschermak §
they have been put out unabridged both in their original form ||
and in English translation, T[ and have been explained by several
writers. ** For convenience of reference I shall however give a
brief outline of Mendel's results and conclusions taken mainly
from my previous paper, ft

When one pure form [A) is crossed with another pure form (a)
the hybrid of the primary cross shows the A characters only.
When, however, the hybrid plants of this generation are fertilized

* Mendel, Versuche Uber Pflanzen-Hybriden. Abh. Naturf. Ver. Briinn, 4:3.
1866.

t De' Vries, Das Spaltungsgesetz dcr Bastarde. Bcr. Deuts. Bot. Gesells. 18 :
85. 1900; Ueber erbungleicbe Kreuzungen. Ber. Deuts. Bot. Gesells. 18 : 435. 1900;
Snr les unites des caract^res sp^cifiques et leur application a I'^tude des hybrides.
RcT. G^n. Bot. 12 : 257. 1900.

X Correns, G. Mendel's Kegel ilber das Verhalten der Nachkommenschaft der
Rassenbastarde. Ber. Deuts. Bot. Ges. 18 : 158. 1900 ; Gregor Mendel's ** Versuche
fiber Pflanzen-Hybriden " unddie Best^tigung ihrer Ergebnisse durch die neuesten Un-
tersuchuDgen. Bot. Zeit. 58* : 229. I9CX>.

{Tschermak, Ueber kiinstliche Kreuzung bei Pisum sativum, Zeitschr. Landw.
Versuchswesen Ocsterr. 5 : 465. 1900 ; Ber. Deuts. Bot. Gesells. 18 : 232. 1900.

II Ostwald's Klassiker der exakten Wissenschaften, No. 121. 1901.

^Jour. Roy. Hort. Soc. Lond. 26: I. AUI901.

** Bateson & Saunders, Experimental Studies in the Physiology of Heredity. Rep.
Evolution Committee Roy. Soc., Report i. 1902; Emerson, Agric. Exp. Sta. Neb.
Rep. 15: 30. 1902; Spillman, Science, II. 16: 709. 1902; Pop. Sci. Month.
62 : 269. Ja 1903.

tt Cannon, A Cytological Basis for the Mendelian Laws. Bull. Torrey Club, 29 :
657. D 1902



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138



Cannon : Studies in Plant Hybrids



among themselves and produce offspring the a characters are seen,
and in a definite proportion to the form bearing the A characters.
These constitute the hybrids of the second generation. If now
the hybrids of the second generation are fertilized in such a man-
ner that plants with a characters are crossed with those bearing
the same characters, and likewise plants bearing A characters with
forms like themselves, the resulting hybrids will behave in a man-
ner characteristic of the respective cross. That is (i) the plants
with a characters will be found to transmit those characters only,
/. e, they are " fixed " ; and (2) when the plants with A characters
are fertilized with other plants bearing the same characters, that is
to say, if inbred, two sorts of hybrids will result : one portion will
bear only the A characters, which may be demonstrated by breed-
ing as before, and one portion, apparently also with A characters
only, will be found to vary just as the hybrids of the primary cross
varied, i, e. this will be really mixed or hybrid. This general
scheme may be better understood if tabulated as follows :



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