Popular Scientific Recreations / in Natural Philosphy, Astronomy, Geology, Chemistry, etc., etc., etc. - Gaston Tissandier

The Artificial or Linnæan System of Classification.

In this system plants are divided into twenty-four classes; twenty-three of these contain the Dicotyledons and Monocotyledons indiscriminately; the twenty-fourth class contains the Acotyledons.

The first twenty-three classes are founded on the number, position, relative lengths, and connection of the stamens. The twenty-fourth comprises the plants with inconspicuous flowers. Every class is subdivided again into several orders. This division depends, in the first thirteen classes, on the number of the styles; in classes XIV. and XV. on the nature of the fruit; in classes XVI. to XVIII. and XX. to XXII. on the number of stamens; in classes XIX. and XXIII. on the perfection of the flower. In class XXIV. the orders are formed according to natural affinities.

Tabular View of the Linnæan System of Classification.

A.—Flowers Present (Phanerogamia).
	I. Stamens and pistil in every flower (hermaphrodite).
	1. Stamens free.
		a. Stamens of equal length, or not differing in definite proportions.
	Number of Stamens.
		1		Class	1. Monandria.
		2		“	2. Diandria.
		3		“	3. Triandria.
		4		“	4. Tetrandria.
		5		“	5. Pentandria.
		6		“	6. Hexandria.
		7		“	7. Heptandria.
		8		“	8. Octandria.
		9		“	9. Enneandria.
		10		“	10. Decandria.
		11-19		“	11. Dodecandria.
		20 or more	inserted on calyx	“	12. Icosandria.
		20 or more	inserted on receptacle	“	13. Polyandria.
	b. Stamens of different lengths, two long and two short			“	14. Didynamia.
	Stamens of different lengths, four long and two short			“	15. Tetradynamia
	2. Stamens united by filaments in one bundle			“	16. Monadelphia.
	Stamens united by filaments in two bundles			“	17. Diadelphia.
	Stamens united by filaments in more than two bundles			“	18. Polyadelphia.
	Stamens united by anthers (compound flowers)			“	19. Syngenesia.
	Stamens united with pistil on a column			“	20. Gynandria.
	II. Stamens and pistil in different flowers (unisexual) on the
	same plant			“	21. Monœcia.
	on different plants			“	22. Diœcia.
	III. Stamens and pistil in the same or in different flowers, on the same or on different plants			“	23. Polygamia.
B.—Flowers Absent				“	24. Cryptogamia

Tabular View of Classes and Orders.

Classes.	Orders.		Examples.
I.—Monandria	Monogynia	one style	Hippuris.
One stamen.	Digynia	two styles	Callitriche.
II.—Diandria	Monogynia	one style	Syringa.
Two stamens.	Digynia	two styles	Anthoxanthum.
	Trigynia	three do.
III.—Triandria	Monogynia	one style	Iris.
Three stamens.	Digynia	two styles	Hordeum.
	Trigynia	three do.	Holosteum.
IV.—Tetrandria	Monogynia	one style	Scabiosa.
Four stamens.	Digynia	two styles	Gentiana.
	Trigynia	three do.
V.—Pentandria	Monogynia	one style	Borago.
Five stamens.	Digynia	two styles	Fœniculum.
	Trigynia	three do.	Sambucus.
	Tetragynia	four do.	Parnassia.
	Pentagynia	five do.	Linum.
	Polygynia	six and more do.	Myosurus.
VI.—Hexandria	Monogynia	one style	Lilium.
Six stamens.	Digynia	two styles	Oxyria.
	Trigynia	three do.	Rumex.
	Tetragynia	four do.	Alisma.
	Polygynia	many do.
VII.—Heptandria	Monogynia	one style	Trientalis.
Seven stamens.	Digynia	two styles
	Trigynia	three do.
	Heptagynia	seven do.
VIII.—Octandria	Monogynia	one style	Daphne.
Eight stamens.	Digynia	two styles	Chrysosplenium.
	Trigynia	three do.	Polygonum.
	Tetragynia	four do.	Paris.
IX.—Enneandria	Monogynia	one style
Nine stamens.	Trigynia	three styles
	Hexagynia	six do.	Butomus.
X.—Decandria	Monogynia	one style	Pyrola.
Ten stamens.	Digynia	two styles	Dianthus.
	Trigynia	three do.	Silene.
	Pentagynia	five do.	Lychnis.
	Decagynia	ten	do.
XI.—Dodecandria	Monogynia	one style	Lythrum.
Twelve to nineteen stamens.	Digynia	two styles	Agrimonia.
	Trigynia	three do.	Reseda.
	Pentagynia	five do.
	Dodecagynia	twelve do.	Sempervivum.
XII.—Icosandria	Monogynia	one style	Prunus.
Twenty or more stamens inserted on the calyx.	Digynia	two styles	Cratægus.
	Trigynia	three do.	Sorbus.
	Pentagynia	five do.
	Polygynia	many do.	Rosa.
XIII.—Polyandria	Monogynia	one style	Papaver.
Many stamens inserted on the receptacle.	Digynia	two styles	Pæonia.
	Trigynia	three do.	Aconitum.
	Tetragynia	four do.
	Pentagynia	five do.	Nigella.
	Hexagynia	six	do.
	Polygynia	many do.	Ranunculus.
XIV.—Didynamia	Gymnospermia	four naked seeds	Lavandula.
Two long and two short stamens. Labiate and Personate Flowers.	Angiospermia	seeds in capsules	Linaria.
XV.—Tetradynamia	Siliculosa	broad and short pod (silicula), and style	Capsella.
Four long and two short stamens. Cruciferous Flowers.	Siliquosa	long pod (siliqua); stigma sessile	Brassica.
XVI.—Monadelphia	Pentandria	five stamens	Erodium.
Stamens united in one bundle.	Enneandria	nine do.
Stamens united in one bundle.	Decandria	ten do.	Geranium.
	Dodecandria	11-19 do.	Malva.
	Polyandria	many do.
XVII.—Diadelphia	Pentandria	five stamens (two above and three below.)
Stamens united in two bundles (one generally containing nine enclosed in a tube, and one free). Papilionaceæ.
	Hexandria	six stamens (three right, three left, or three above and three below.)	Fumaria.
	Octandria	eight stamens (four above and four below, all united at the base.)	Polygala.
	Decandria	ten stamens (one above and nine below, united in a cleft tube surrounding the ovary.)	Pisum, Trifolium, Genista.
XVIII.—Polyadelphia	Pentandria	five bundles (each bundle bearing five anthers = 25 stamens.)
Stamens united in more than two bundles.	Dodecandria	twelve stamens (each bundle bearing three anthers = 36 stamens.)
Stamens united in more than two bundles.	Icosandria	many stamens in bundles, inserted on the calyx (20 stamens in bundles bearing an unequal number of anthers.)	Citrus.
	Polyandria	many stamens in three, five, and nine bundles, inserted on the receptacle.	Hypericum.
XIX.—Syngenesia	Polygamia æqualia, florets all hermaphrodite.		Lactuca.
Five stamens, filaments free, anthers united, flower monopetalous, florets united on a disc. Compositæ. In the first four orders only a common calyx.
	Polygamia superflua, florets of the disc hermaphrodite, those of the ray pistilliferous and fertile.		Aster.
	Polygamia frustranea, florets of the disc hermaphrodite, those of the ray neutral.		Helianthus.
	Polygamia necessaria, florets of the disc staminiferous, of the ray pistilliferous		Calendula.
	Polygamia segregata, a common calyx including all the florets, and a separate involucre for each.		Echinops.
	Monogamia, anthers united, flowers not compound.
XX.—Gynandria	Diandria	two anthers	Orchis.
Stamens and pistil united.	Triandria	three do.
	Tetrandria	four do.
	Pentandria	five do.
	Hexandria	six do.	Aristolochia.
	Decandria	ten do.
	Dodecandria	11-19 do.
	Polyandria	twenty or more do.
XXI.—Monœcia	Monandria	one stamen	Arum.
Stamens and pistils in different flowers on the same plant.	Diandria	two stamens	Lemna.
Stamens and pistils in different flowers on the same plant.	Triandria	three do.	Carex.
	Tetrandria	four do.	Urtica.
	Pentandria	five do.	Amaranthus.
	Hexandria	six do.
	Heptandria	seven do.
	Polyandria	more than seven do.	Quercus.
	Monadelphia	stamens united	Pinus.
	Syngenesia	stamens united by their anthers.
	Gynandria	stamens and styles united
XXII.—Diœcia	Monandria	one stamen	Salix.
Stamens and pistils in different flowers on different plants.	Diandria	two stamens
	Triandria	three do.	Ficus.
	Tetrandria	four do.	Viscum.
	Pentandria	five do.	Cannabis.
	Hexandria	six do.	Loranthus.
	Octandria	eight do.	Populus.
	Enneandria	nine do.	Laurus.
	Decandria	ten do.
	Dodecandria	11-19 do.	Stratiotes.
	Polyandria	many	do.
	Monadelphia	stamens united in one bundle.	Juniperus.
	Syngenesia	stamens united by	the anthers.
	Gynandria	stamens and styles united.	united.
XXIII.—Polygamia	Monœcia, hermaphrodite, staminiferous, and pistilliferous flowers on the	same plant.	Acer.
Stamens and pistil in the same, or in different flowers, on the same or on different plants.
	Diœcia	on two plants	Fraxinus.
	Triœcia	on three plants
XXIV.—Cryptogamia	Filices	Ferns	Aspidium.
Organs of fructification concealed (flowers inconspicuous).	Musci	Mosses	Spagnum.
	Hepaticæ	Liverworts	Marchantia.
	Lichenes	Lichens	Cetraria.
	Algæ	Seaweeds	Fucus.
	Fungi	Mushrooms	Agaricus.

With all its imperfections, the artificial system has this advantage, that the character on which it is founded is sufficiently conspicuous (that is, of course, with the plants in full flower) to render it generally easy to ascertain the class and order of a plant. At all events, it may serve as a useful artificial key, and as such may be combined advantageously with the natural system.