519. Classification, in botany, is the consideration of plants in
respect to their kinds and relationships. Some system of Nomenclature,
or naming, is necessary for fixing and expressing botanical knowledge so
as to make it available. The vast multiplicity of plants and the various
degrees of their relationship imperatively require order and system, not
only as to _names_ for designating the kinds of plants, but also as to
_terms_ for defining their differences. Nomenclature is concerned with
the names of plants. Terminology supplies names of organs or parts, and
terms to designate their differences.
Sec. 1. KINDS AND RELATIONSHIP.
520. Plants and animals have two great peculiarities: 1st, they form
themselves; and 2d, they multiply themselves. They reproduce their kind
in a continued succession of
521. =Individuals.= Mineral things occur as _masses_, which are
divisible into smaller and still smaller ones without alteration of
properties. But organic things (vegetables and animals) exist as
_individual beings_. Each owes its existence to a parent, and produces
similar individuals in its turn. So each individual is a link of a
chain; and to this chain the natural-historian applies the name of
522. =Species.= All the descendants from the same stock therefore
compose one species. And it was from our observing that the several
sorts of plants or animals steadily reproduce themselves, or, in other
words, keep up a succession of similar individuals, that the idea of
species originated. There are few species, however, in which man has
actually observed the succession for many generations. It could seldom
be proved that all the White Pine trees or White Oaks of any forest came
from the same stock. But observation having familiarized us with the
general fact that individuals proceeding from the same stock are
essentially alike, we infer from their close resemblance that these
similar individuals belong to the same species. That is, we infer it
when the individuals are as much like each other as those are which we
know, or confidently suppose, to have sprung from the same stock.
523. Identity in species is inferred from close similarity in all
essential respects, or whenever the differences, however considerable,
are not known or reasonably supposed to have been originated in the
course of time under changed conditions. No two individuals are exactly
alike; a tendency to variation pervades all living things. In
cultivation, where variations are looked after and cared for, very
striking differences come to light; and if in wild nature they are less
common or less conspicuous, it is partly because they are uncared for.
When such variant forms are pretty well marked they are called
524. =Varieties.= The White Oak, for example, presents two or three
varieties in the shape of the leaves, although they may be all alike
upon each particular tree. The question often arises, and it is often
hard to answer, whether the difference in a particular case is that of a
variety, or is specific. If the former, it may commonly be proved by
finding such intermediate degrees of difference in various individuals
as to show that no clear distinction can be drawn between them; or else
by observing the variety to vary back again in some of its offspring.
The sorts of Apples, Pears, Potatoes, and the like, show that
differences which are permanent in the individual, and continue
unchanged through a long series of generations when propagated by
division (as by offsets, cuttings, grafts, bulbs, tubers, etc.), are not
likely to be reproduced by seed. Still they sometimes are so, and
perhaps always tend in that direction. For the fundamental law in
organic nature is that offspring shall be like parent.
RACES are such strongly marked varieties, capable of coming true to
seed. The different sorts of Wheat, Maize, Peas, Radishes, etc., are
familiar examples. By selecting those individuals of a species which
have developed or inherited any desirable peculiarity, keeping them from
mingling with their less promising brethren, and selecting again the
most promising plants raised from their seeds, the cultivator may in a
few generations render almost any variety transmissible by seed, so long
as it is cared for and kept apart. In fact, this is the way the
cultivated domesticated races, so useful to man, have been fixed and
preserved. Races, in fact, can hardly, if at all, be said to exist
independently of man. But man does not really produce them. Such
peculiarities--often surprising enough--now and then originate, we know
not how (the plant _sports_, as the gardeners say); they are only
preserved, propagated, and generally further developed, by the
cultivator's skilful care. If left alone, they are likely to dwindle and
perish, or else revert to the original form of the species. Vegetable
races are commonly annuals, which can be kept up only by seed, or herbs
of which a succession of generations can be had every year or two, and
so the education by selection be completed without great lapse of time.
But all fruit-trees could probably be fixed into races in an equal
number of generations.
BUD-VARIETIES are those which spring from buds instead of seed. They are
uncommon to any marked extent. They are sometimes called _Sports_, but
this name is equally applied to variations among seedlings.
CROSS-BREEDS, strictly so-called, are the variations which come from
cross-fertilizing one variety of a species with another.
HYBRIDS are the varieties, if they may be so called,--which come from
the crossing of species (331). Only nearly related species can be
hybridized; and the resulting progeny is usually self-sterile, but not
always. Hybrid plants, however, may often be fertilized and made
prolific by the pollen of one or the other parent. This produces another
kind of cross-breeds.
525. Species are the units in classification. Varieties, although of
utmost importance in cultivation and of considerable consequence in the
flora of any country, are of less botanical significance. For they are
apt to be indefinite and to shade off one form into another. But
species, the botanist _expects_ to be distinct. Indeed, the practical
difference to the botanist between species and varieties is the definite
limitation of the one and the indefiniteness of the other. The
botanist's determination is partly a matter of observation, partly of
judgment.
526. In an enlarged view, varieties may be incipient species; and nearly
related species probably came from a common stock in earlier times. For
there is every reason to believe that existing vegetation came from the
more or less changed vegetation of a preceding geological era. However
that may be, species are regarded as permanent and essentially unchanged
in their succession of individuals through the actual ages.
527. There are, at nearly the lowest computation, as many as one hundred
thousand species of phanerogamous plants, and the cryptogamous species
are thought to be still more numerous. They are all connected by
resemblances or relationships, near and remote, which show that they are
all parts of one system, realizations in nature, as we may affirm, of
the conception of One Mind. As we survey them, they do not form a single
and connected chain, stretching from the lowest to the highest organized
species, although there obviously are lower and higher grades. But the
species throughout group themselves, as it were, into clusters or
constellations, and these into still more comprehensive clusters, and so
on, with gaps between. It is this clustering which is the ground of the
recognition of _kinds_ of species, that is, of groups of species of
successive grades or degree of generality; such as that of similar
species into _Genera_, of genera into _Families_ or _Orders_, of orders
into _Classes_. In classification the sequence, proceeding from higher
or more general to lower or special, is always CLASS, ORDER, GENUS,
SPECIES, VARIETY (if need be).
528. =Genera= (in the singular, _Genus_) are assemblages of closely
related species, in which the essential parts are all constructed on the
same particular type or plan. White Oak, Red Oak, Scarlet Oak, Live Oak,
etc., are so many species of the Oak genus (Latin, _Quercus_). The
Chestnuts compose another genus; the Beeches another. The Apple, Pear,
and Crab are species of one genus, the Quince represents another, the
various species of Hawthorn a third. In the animal kingdom the common
cat, the wild-cat, the panther, the tiger, the leopard, and the lion are
species of the cat kind or genus; while the dog, the jackal, the
different species of wolf, and the foxes, compose another genus. Some
genera are represented by a vast number of species, others by few, very
many by only one known species. For the genus may be as perfectly
represented in one species as in several, although, if this were the
case throughout, genera and species would of course be identical. The
Beech genus and the Chestnut genus would be just as distinct from the
Oak genus even if but one Beech and Chestnut were known; as indeed was
once the case.
529. =Orders= are groups of genera that resemble each other; that is,
they are to genera what genera are to species. As familiar
illustrations, the Oak, Chestnut, and Beech genera, along with the Hazel
genus and the Hornbeams, all belong to one order. The Birches and the
Alders make another; the Poplars and Willows, another; the Walnuts (with
the Butternut) and the Hickories, still another. The Apple genus, the
Quince and the Hawthorns, along with the Plums and Cherries and the
Peach, the Raspberry with the Blackberry, the Strawberry, the Rose,
belong to a large order, which takes its name from the Rose. Most
botanists use the names "Order" and "Family" synonymously; the latter
more popularly, as "the Rose Family," the former more technically, as
"Order _Rosaceae_."
530. But when the two are distinguished, as is common in zoology, Family
is of lower grade than Order.
531. =Classes= are still more comprehensive assemblages, or great
groups. Thus, in modern botany, the Dicotyledonous plants compose one
class, the Monocotyledonous plants another (36-40).
532. These four grades, Class, Order, Genus, Species, are of universal
use. Variety comes in upon occasion. For, although a species may have no
recognized varieties, a genus implies at least one species belonging to
it; every genus is of some order, and every order of some class.
533. But these grades by no means exhaust the resources of
classification, nor suffice for the elucidation of all the distinctions
which botanists recognize. In the first place, a higher grade than that
of class is needful for the most comprehensive of divisions, that of all
plants into the two _Series_ of Phanerogamous and Cryptogamous (6); and
in natural history there are the two _Kingdoms_ or _Realms_, the
Vegetable and the Animal.
534. Moreover, the stages of the scaffolding have been variously
extended, as required, by the recognition of assemblages lower than
class but higher than order, viz. _Subclass_ and _Cohort_; or lower than
order, a _Suborder_; or between this and genus, a _Tribe_; or between
this and tribe, a _Subtribe_; or between genus and species, a
_Subgenus_; and by some a species has been divided into _Subspecies_,
and a variety into _Subvarieties_. Last of all are _Individuals_.
Suffice it to remember that the following are the principal grades in
classification, with the proper sequence; also that only those here
printed in small capitals are fundamental and universal in botany:--
SERIES,
CLASS, Subclass, Cohort,
ORDER, or FAMILY, Suborder, Tribe, Subtribe,
GENUS, Subgenus or Section,
SPECIES, Variety.
Sec. 2. NAMES, TERMS, AND CHARACTERS.
535. The name of a plant is the name of its genus followed by that of
the species. The name of the genus answers to the surname (or family
name); that of the species to the baptismal name of a person. Thus
_Quercus_ is the name of the Oak genus; _Quercus alba_, that of the
White Oak, _Q. rubra_, that of Red Oak, _Q. nigra_, that of the
Black-Jack, etc. Botanical names being Latin or Latinized, the adjective
name of the species comes after that of the genus.
536. =Names of Genera= are of one word, a substantive. The older ones
are mostly classical Latin, or Greek adopted into Latin; such as
_Quercus_ for the Oak genus, _Fagus_ for the Beech, _Corylus_, the
Hazel, and the like. But as more genera became known, botanists had new
names to make or borrow. Many are named from some appearance or property
of the flowers, leaves, or other parts of the plant. To take a few
examples from the early pages of the "Manual of the Botany of the
Northern United States,"--the genus _Hepatica_ comes from the shape of
the leaf, resembling that of the liver. _Myosurus_ means mouse-tail.
_Delphinium_ is from delphin, a dolphin, and alludes to the shape of the
flower, which was thought to resemble the classical figures of the
dolphin. _Xanthorrhiza_ is from two Greek words meaning yellow-root, the
common name of the plant. _Cimicifuga_ is formed of two Latin words
meaning to drive away bugs, i. e. Bugbane, the Siberian species being
used to keep away such vermin. _Sanguinaria_, the Bloodroot, is named
from the blood-like color of its juice. Other genera are dedicated to
distinguished botanists or promoters of science, and bear their names:
such are _Magnolia_, which commemorates the early French botanist,
Magnol; and _Jeffersonia_, named after President Jefferson, who sent the
first exploring expedition over the Rocky Mountains. Others bear the
name of the discoverer of the plant; as, _Sarracenia_, dedicated to Dr.
Sarrazin, of Quebec, who was one of the first to send the common
Pitcher-plant to the botanists of Europe; and _Claytonia_, first made
known by the early Virginian botanist Clayton.
537. =Names of Species.= The name of a species is also a single word,
appended to that of the genus. It is commonly an adjective, and
therefore agrees with the generic name in case, gender, etc. Sometimes
it relates to the country the species inhabits; as, Claytonia
_Virginica_, first made known from Virginia; Sanguinaria _Canadensis_,
from Canada, etc. More commonly it denotes some obvious or
characteristic trait of the species; as, for example, in Sarracenia, our
northern species is named _purpurea_, from the purple blossoms, while a
more southern one is named _flava_, because its petals are yellow; the
species of Jeffersonia is called _diphylla_, meaning two-leaved, because
its leaf is divided into two leaflets. Some species are named after the
discoverer, or in compliment to a botanist who has made them known; as,
Magnolia _Fraseri_, named after the botanist Fraser, one of the first
to find this species; and Sarracenia _Drummondii_, for a Pitcher-plant
found by Mr. Drummond in Florida. Such personal specific names are of
course written with a capital initial letter. Occasionally some old
substantive name is used for the species; as Magnolia _Umbrella_, the
Umbrella tree, and Ranunculus _Flammula_. These are also written with a
capital initial, and need not accord with the generic name in gender.
Geographical specific names, such as _Canadensis_, _Caroliniana_,
_Americana_, in the later usage are by some written without a capital
initial, but the older usage is better, or at least more accordant with
English orthography.
538. =Varietal Names=, when any are required, are made on the plan of
specific names, and follow these, with the prefix _var_. Ranunculus
Flammula, var. _reptans_, the creeping variety: R. abortivus, var.
_micranthus_, the small-flowered variety of the species.
539. In recording the name of a plant it is usual to append the name, or
an abbreviation of the name, of the botanist who first published it; and
in a flora or other systematic work, this reference to the source of the
name is completed by a further citation of the name of the book, the
volume and page where it was first published. So "_Ranunculus acris_,
L.," means that this Buttercup was first so named and described by
Linnaeus; "_R. multifidus_, Pursh," that this species was so named and
published by Pursh. The suffix is no part of the name, but is an
abbreviated reference, to be added or omitted as convenience or
definiteness may require. The authority for a generic name is similarly
recorded. Thus, "_Ranunculus_, L.," means that the genus was so named by
Linnaeus; "_Myosurus_, Dill.," that the Mouse-tail was established as a
genus under this name by Dillenius; _Caulophyllum_, Michx., that the
Blue Cohosh was published under this name by Michaux. The full reference
in the last-named instance would be, "in Flora Boreali-Americana, first
volume, 205th page,"--in the customary abbreviation, "Michx. Fl. i.
205."
540. =Names of Orders= are given in the plural number, and are commonly
formed by prolonging the name of a genus of the group taken as a
representative of it. For example, the order of which the Buttercup or
Crowfoot genus, _Ranunculus_, is the representative, takes from it the
name of _Ranunculaceae_; meaning _Plantae Ranunculaceae_ when written out
in full, that is, Ranunculaceous Plants. Some old descriptive names of
orders are kept up, such as _Cruciferae_ for the order to which Cress and
Mustard belong, from the cruciform appearance of their expanded corolla,
and _Umbelliferae_, from the flowers being in umbels.
541. =Names of Tribes=, also of suborders, subtribes, and the like, are
plurals of the name of the typical genus, less prolonged, usually in
_eae_, _ineae_, _ideae_, etc. Thus the proper Buttercup tribe is
_Ranunculeae_, of the Clematis tribe, _Clematideae_. While the Rose family
is _Rosaceae_, the special Rose tribe is _Roseae_.
542. =Names of Classes, etc.= For these see the following synopsis of
the actual classification adopted, p. 183.
543. So a plant is named in two words, the generic and the specific
names, to which may be added a third, that of the variety, upon
occasion. The generic name is peculiar: obviously it must not be used
twice over in botany. The specific name must not be used twice over in
the same genus, but is free for any other genus. A _Quercus alba_, or
White Oak, is no hindrance to _Betula alba_, or White Birch; and so of
other names.
544. =Characters and Descriptions.= Plants are _characterized_ by a
terse statement, in botanical terms, of their peculiarities or
distinguishing marks. The character of the order should include nothing
which is common to the whole class it belongs to; that of the genus,
nothing which is common to the order; that of the species nothing which
is shared with all other species of the genus; and so of other
divisions. _Descriptions_ may enter into complete details of the whole
structure.
545. =Terminology=, also called _Glossology_, is nomenclature applied to
organs or parts, and their forms or modifications. Each organ or special
part has a substantive name of its own: shapes and other modifications
of an organ or part are designated by adjective terms, or, when the
forms are peculiar, substantive names are given to them. By the correct
use of such botanical terms, and by proper subordination of the
characters under the order, genus, species, etc., plants may be
described and determined with much precision. The classical language of
botany is Latin. While modern languages have their own names and terms,
these usually lack the precision of the Latin or Latinized botanical
terminology. Fortunately, this Latinized terminology has been largely
adopted and incorporated into the English technical language of botany,
thus securing precision. And these terms are largely the basis of
specific names of plants.
546. A glossary or vocabulary of the principal botanical terms used in
phanerogamous and vascular cryptogamous botany is appended to this
volume, to which the student may refer, as occasion arises.
Sec. 3. SYSTEM.
547. Two systems of classification used to be recognized in botany,--the
artificial and the natural; but only the latter is now thought to
deserve the name of a system.
548. Artificial classifications have for object merely the ascertaining
of the name and place of a plant. They do not attempt to express
relationships, but serve as a kind of dictionary. They distribute the
genera and species according to some one peculiarity or set of
peculiarities (just as a dictionary distributes words according to their
first letters), disregarding all other considerations. At present an
artificial classification in botany is needed only as a key to the
natural orders,--as an aid in referring an unknown plant to its proper
family; and such keys are still very needful, at least for the beginner.
Formerly, when the orders themselves were not clearly made out, an
artificial classification was required to lead the student down to the
genus. Two such classifications were long in vogue: First, that of
Tournefort, founded mainly on the leaves of the flower, the calyx and
corolla: this was the prevalent system throughout the first half of the
eighteenth century; but it has long since gone by. It was succeeded by
the well-known
549. =Artificial System of Linnaeus=, which was founded on the stamens
and pistils. It consists of twenty-four classes, and of a variable
number of orders; the classes founded mainly on the number and
disposition of the stamens; the orders partly upon the number of styles
or stigmas, partly upon other considerations. Useful and popular as this
system was down to a time within the memory of still surviving
botanists, it is now completely obsolete. But the tradition of it
survives in the names of its classes, Monandria, Diandria, Triandria,
etc., which are familiar in terminology in the adjective terms
monandrous, diandrous, triandrous, etc. (284); also of the orders,
Monogynia, Digynia, Trigynia, etc., preserved in the form of monogynous,
digynous, trigynous, etc. (301); and in the name Cryptogamia, that of
the 24th class, which is continued for the lower series in the natural
classification.
550. =Natural System.= A genuine system of botany consists of the orders
or families, duly arranged under their classes, and having the tribes,
the genera, and the species arranged in them according to their
relationships. This, when properly carried out, is the _Natural System_;
because it is intended to express, as well as possible, the various
degrees of relationship among plants, as presented in nature; that is,
to rank those species and those genera, etc., next to each other in the
classification which are really most alike in all respects, or, in other
words, which are constructed most nearly on the same particular plan.
551. There can be only _one_ natural system of botany, if by this term
is meant the plan according to which the vegetable creation was called
into being, with all its grades and diversities among the species, as
well of past as of the present time. But there may be many natural
systems, if we mean the attempts of men to interpret and express that
plan,--systems which will vary with advancing knowledge, and with the
judgment and skill of different botanists. These must all be very
imperfect, bear the impress of individual minds, and be shaped by the
current philosophy of the age. But the endeavor always is to make the
classification answer to Nature, as far as any system can which has to
be expressed in a definite and serial arrangement.
552. So, although the classes, orders, genera, etc., are natural, or as
natural as the systematist can make them, their grouping or order of
arrangement in a book, must necessarily be in great measure artificial.
Indeed, it is quite impossible to arrange the orders, or even the few
classes, in a single series, and yet have each group stand next to its
nearest relatives on both sides.
553. Especially it should be understood that, although phanerogamous
plants are of higher grade than cryptogamous, and angiospermous or
ordinary phanerogamous higher than the gymnospermous, yet there is no
culmination in the vegetable kingdom, nor any highest or lowest order of
phanerogamous plants.
554. The particular system most largely used at present in the
classification of the orders is essentially the following:--
SERIES I. PHANEROGAMIA: PHANEROGAMOUS OR FLOWERING PLANTS.
CLASS I. DICOTYLEDONES ANGIOSPERMEAE, called for shortness in
English, DICOTYLEDONS or DICOTYLS. Ovules in a closed ovary.
Embryo dicotyledonous. Stem with exogenous plan of growth. Leaves
reticulate-veined,
_Artificial Division I._ POLYPETALAE, with petals mostly present
and distinct. Orders about 80 in number, _Ranunculaceae_ to
_Cornaceae_.
_Artificial Division II._ GAMOPETALAE, with gamopetalous corolla.
Orders about 45, _Caprifoliaceae_ to _Plantaginaceae_.
_Artificial Division III._ APETALAE or INCOMPLETAE, with perianth,
when present, of calyx only. Orders about 35 in number, from
_Nyctaginaceae_ to _Salicaceae_.
CLASS II. DICOTYLEDONES GYMNOSPERMEAE, in English GYMNOSPERMS. No
ovary or pericarp, but ovules and seeds naked, and no proper calyx
nor corolla. Embryo dicotyledonous or polycotyledonous. Stem with
exogenous plan of growth. Leaves mostly parallel-veined. Consists
of order _Gnetaceae_, which strictly connects with Angiospermous
Dicotyls, of _Coniferae_, and of _Cycadaceae_.
CLASS III. MONOCOTYLEDONES, in English MONOCOTYLEDONS or
MONOCOTYLS. Angiospermous. Embryo monocotyledonous. Stem with
endogenous plan of growth. Leaves mostly parallel-veined.
_Division I._ PETALOIDEAE. Perianth complete, having the
equivalent of both calyx and corolla, and all the inner series
corolline. About 18 orders.
_Division II._ CALYCINAE. Perianth complete (in two series) but
not corolline, mostly thickish or glumaceous. Chiefly two
orders, _Juncaceae_, the true Rushes, and _Palmae_, Palms.
_Division III._ SPADICIFLORAE or NUDIFLORAE. Perianth none, or
rudimentary and incomplete: inflorescence spadiceous. Of five
orders, _Typhaceae_ and _Aroideae_ the principal.
_Division IV._ GLUMACEAE. Perianth none, or very rudimentary:
glumaceous bracts to the flowers. Orders mainly _Cyperaceae_ and
_Gramineae_.
SERIES II. CRYPTOGAMIA: CRYPTOGAMOUS OR FLOWERLESS PLANTS.
CLASS I. PTERIDOPHYTA, PTERIDOPHYTES (484).
CLASS II. BRYOPHYTA, BRYOPHYTES (498).
CLASS III. THALLOPHYTA, THALLOPHYTES (503).