Chapter XXIV: Appendix: On the Classification of Plants

BY M. C. POTTER.

The earliest systems of classification were derived from the properties and uses of plants; and it was not until some two centuries ago that any scientific grouping of plants was attempted. Aristotle and Theophrastus had adopted the groups of Trees, Shrubs and Herbs as the chief divisions of the Vegetable Kingdom, a system which persisted and was employed by Tournefort and Ray as late as the end of the 17th century. The arrangement by which these three divisions were separated into smaller divisions was often founded upon a single character, such as the formation of the corolla, the form of fruit, that of the calyx and corolla, etc. All these systems of classification which brought into close proximity plants distinguished by some one character alone, could only be considered as _artificial_, since plants related to one another would not necessarily be included in the same group. As the knowledge of the morphology, physiology, and reproduction of plants increased, such systems were recognised as unscientific, and it became the aim of botanists to establish a _natural_ system, founded upon mutual relationships, which would associate together _only_ those plants which are truly allied.

The following are some of the chief systems of classification which will show the gradual development of the natural system, and may be of service to students making use of this text-book.[41]

System of JOHN RAY (1703).

I. Herbæ.
A. IMPERFECTÆ (Flowerless).
B. PERFECTÆ (Flowering).
_Dicotyledones_.
_Monocotyledones._
II. Arbores.
A. _Monocotyledones._
B. _Dicotyledones._

Ray was the first botanist who recognised the importance of the one or two seed-leaves of the embryo, and initiated the division of the Flowering-plants into Monocotyledons and Dicotyledons.

System of LINNÆUS (1733).

In his well known artificial system Linnæus divided the Vegetable Kingdom into twenty-four classes, based upon the number, relative position and union of the stamens with regard to each other, and also to the gynœceum.

Class I. MONANDRIA. Flowers with 1 stamen.
„ II. DIANDRIA. „ „ 2 stamens.
„ III. TRIANDRIA. „ „ 3 „
„ IV. TETRANDRIA. „ „ 4 „
„ V. PENTANDRIA. „ „ 5 „
„ VI. HEXANDRIA. „ „ 6 „
„ VII. HEPTANDRIA. „ „ 7 „
„ VIII. OCTANDRIA. „ „ 8 „
„ IX. ENNEANDRIA. „ „ 9 „
„ X. DECANDRIA. „ „ 10 „
„ XI. DODECANDRIA. „ „ 11 to 19 stamens.
„ XII. ICOSANDRIA. „ „ 20 or more stamens inserted
on the calyx.
„ XIII. POLYANDRIA. „ „ 20 or more stamens inserted
on the receptacle.
„ XIV. DIDYNAMIA. Stamens didynamous.
„ XV. TETRADYNAMIA. „ tetradynamous.
„ XVI. MONADELPHIA. Filaments united into 1 bundle.
„ XVII. DIADELPHIA. „ „ „ 2 bundles.
„ XVIII. POLYADELPHIA. „ „ „ several bundles.
„ XIX. SYNGENESIA. Anthers united together.
„ XX. GYNANDRIA. Stamens and pistil united.
„ XXI. MONŒCIA. Flowers diclinous, ♂ and ♀ on the same
plant.
„ XXII. DIŒCIA. „ „ ♂ and ♀ on different
plants.
„ XXIII. POLYGAMIA. ♂-, ♀-, and ☿-flowers on the same plant.
„ XXIV. CRYPTOGAMIA. Flowerless plants (Ferns, Mosses, Algæ,
Fungi).

These classes were further divided into orders, according to the
number of styles, as Monogynia, flowers with 1 style; Digynia,
with 2 styles, etc. Thus a Dock (_Rumex_), having 6 stamens and
3 styles, would be placed in Class VI., HEXANDRIA, and Order
III., Trigynia.

Class XIV. was divided into two orders. Order I., Gymnospermia,
with seeds apparently naked, comprising the Labiatæ; and
Order II., Angiospermia, with the seeds enclosed in a capsule
(_Bartsia_, _Rhinanthus_).

Class XV. was divided into two orders: Order I., Siliculosa,
fruit a silicula (_Capsella_); and Order II., Siliquosa, fruit a
siliqua (_Brassica_).

Class XIX. was divided into Order I., Æqualis, all the flowers
perfect (_Sonchus_); Order II., Superflua, flowers in the centre
perfect, those at the circumference with pistils only (seemingly
superfluous), _e.g._ _Aster_; Order III., Frustranea, flowers in
the centre perfect, those at the circumference neuter, _e.g._
_Centaurea_.

“Fragments” of a natural system have also come down to us from
Linnæus, who himself always recognised the imperfection of his
artificial system.

System of ANTOINE LAURENT DE JUSSIEU (1789).

Class
=Acotyledones.= Plants without cotyledons: Fungi, Ferns,
Mosses, Algæ, Naiades I.

=Monoctyledones.= Plants with _one_ cotyledon:--
1. Stamens hypogynous II.
2. „ perigynous III.
3. „ epigynous IV.

=Dicotyledones.= Plants with _two_ cotyledons:--

{ Stamens epigynous V.
1. APETALÆ { „ perigynous VI.
{ „ hypogynous VII.

{ Corolla hypogynous VIII.
2. MONOPETALAE { „ perigynous IX.
{ „ epigynous, {anthers connate X.
{ „ free XI.

{ Stamens epigynous XII.
3. POLYPETALÆ { „ hypogynous XIII.
{ „ perigynous XIV.

4. DICLINES IRREGULARES, male and female flowers on different
plants, corolla generally absent.

System of A. P. DE CANDOLLE (1819).

I. =Vasculares.= Plants with vascular bundles.
1. EXOGENÆ. Vascular bundles arranged in a ring.
A. _Diplochlamydeæ._ Calyx and corolla present.
_a._ Thalamifloræ. Corolla polypetalous and
hypogynous.
_b._ Calycifloræ. Corolla perigynous or epigynous;
stamens inserted on the calyx.
_c._ Corollifloræ. Corolla gamopetalous; stamens
inserted on the corolla.
B. _Monochlamydeæ._ Perianth simple.
2. ENDOGENÆ. Vascular bundles scattered, the youngest in
the centre.
A. _Phanerogamæ._ Flowers present.
B. _Cryptogamæ._ Flowers absent.
II. =Cellulares.= Vascular bundles absent.
1. FOLIACEÆ. Leaves present.
2. APHYLLÆ. Leafless.

ROBERT BROWN published in 1827 his discovery of the gymnospermy of the ovules of the Coniferæ and Cycadeæ, and showed that the Gymnosperms, which had previously been classed with the Dicotyledons, must be regarded as an independent group.

System of STEPHEN ENDLICHER (1836–40).

I. =Thallophyta.= No differentiation into stem and root.
1. PROTOPHYTA. Class I., Algæ; Class II., Lichenes.
2. HYSTEROPHYTA. Class III., Fungi.
II. =Cormophyta.= Differentiated into stem and root.
1. ACROBRYA. Stem growing at the point.
_Anophyta_ (Hepaticæ, Musci).
_Protophyta_ (Filices, etc.).
_Hysterophyta_ (Balanophoreæ, etc.).
2. AMPHIBRYA. Stem growing at the circumference
(Monocotyledons).
3. ACRAMPHIBRYA. Stem growing both at the point and
circumference.
_Gymnosperma_ (Coniferae).
_Apetala._ Perianth single or absent.
_Gamopetala._ Petals gamopetalous.
_Dialypetala._ Petals polypetalous.

System of A. BRONGNIART (1843).

I. =Cryptogamæ.= Plants without flowers.
1. AMPHIGENÆ. Not differentiated into stem or leaf (Algæ,
Fungi, Lichenes).
2. ACROGENÆ. Plants with stem and leaf (Muscineæ, Filicinæ).
II. =Phanerogamæ.= Plants with flowers.
3. MONOCOTYLEDONES.
_a._ Albuminosæ. Seeds with endosperm.
_b._ Exalbuminosæ. Seeds without endosperm.
4. DICOTYLEDONES.
_a._ Angiosepermæ.
α. Gamopetalæ.
β. Dialypetalæ.
_b._ Gymnospermæ.

System of JOHN LINDLEY (_Vegetable Kingdom_, 1845).

Asexual, or Flowerless Plants.

Stem and leaves undistinguishable I. =Thallogens.=
Stem and leaves distinguishable II. =Acrogens.=

Sexual, or Flowering Plants.

Fructification springing from a thallus III. =Rhizogens.=
Fructification springing from a stem.
Wood of stem youngest in the centre; cotyledon
single. Leaves parallel-veined, permanent; wood
of stem always confused IV. =Endogens.=

Leaves net-veined, deciduous; wood of the stem,
when perennial, arranged in a circle with a
central pith V. =Dictyogens.=

Wood of stem youngest at the circumference, always
concentric; cotyledons, 2 or more.
Seeds quite naked VI. =Gymnogens.=
Seeds inclosed in seed-vessels VII. =Exogens.=

System of ALEXANDER BRAUN (1864).

I. =Bryophyta.=
1. THALLODEA (Algæ, Fungi, Lichenes).
2. THALLOPHYLLODEA (Charas, Mosses).
II. =Cormophyta.=
1. PHYLLOPTERIDES (Ferns, Equisetums).
2. MASCHALOPTERIDES (Lycopods).
3. HYDROPTERIDES (Water-ferns).
III. =Anthophyta.=
GYMNOSPERMÆ.
1. _Frondosæ_ (Cycadeæ).
2. _Acerosæ_ (Coniferæ).
ANGIOSPERMÆ.
1. _Monocotyledones._
2. _Dicotyledones._
Apetalæ.
Sympetalæ.
Eleutheropetalæ.

W. HOFMEISTER published from 1849 to 1851 his researches upon the embryology of the Phanerogams, and upon the embryology and life-history of the Vascular Cryptogams, and established the phylogenetic connection existing between the Mosses, Vascular Cryptogams and Phanerogams.

System of HOOKER and BENTHAM (_Genera plantarum_, 1862–1883).

Dicotyledones.

I. Polypetalæ.

Series I. =Thalamifloræ.= Calyx most often free from the ovary. Petals uniseriate or often 2–∞-seriate. Stamens ∞ or definite, inserted on the receptacle, often small, or raised, or stipitate. Ovary most frequently free.

Cohort I. RANALES. Stamens ∞, or if definite the perianth is 3–∞-seriate. Carpels apocarpous, or immersed in the receptacle. Endosperm usually abundant, fleshy.

Order 1. Ranunculaceæ.
„ 2. Dilleniaceæ.
„ 3. Calycanthaceæ.
„ 4. Magnoliaceæ.
„ 5. Anonaceæ.
„ 6. Menispermaceæ.
„ 7. Berberideæ.
„ 8. Nymphæaceæ.

Cohort II. PARIETALES. Stamens ∞ or definite. Ovary unilocular, or divided into loculi by spurious dissepiments, with parietal placentation. Endosperm absent or fleshy.

Order 9. Sarraceniaceæ.
„ 10. Papaveraceæ.
„ 11. Cruciferæ.
„ 12. Capparideæ.
„ 13. Resedaceæ.
„ 14. Cistineæ.
„ 15. Violarieæ.
„ 16. Canellaceæ.
„ 17. Bixineæ.

Cohort III. POLYGALINÆ. Stamens definite. Ovary usually perfectly or imperfectly bilocular. Micropyle often superior. Fruit very often compressed laterally. Endosperm very often abundant and fleshy.

Order 18. Pittosporeæ.
„ 19. Tremandreæ.
„ 20. Polygaleæ.
„ 20_a._ Vochysiaceæ.

Cohort IV. CARYOPHYLLINEÆ. Stamens definite, or rarely ∞. Ovary unilocular, or imperfectly septate. Placenta central, more rarely parietal. Micropyle inferior. Embryo curved, rarely straight. Endosperm farinaceous.

Order 21. Frankeniaceæ.
„ 22. Caryophylleæ.
„ 23. Portulaceæ.
„ 24. Tamariscineæ.

Cohort V. GUTTIFERALES. Sepals inbricate. Stamens usually ∞. Ovary septate, placentæ on the inner angles of the loculi. Endosperm absent or fleshy.

Order 25. Elatineæ.
„ 26. Hypericineæ.
„ 27. Guttiferæ.
„ 28. Ternstrœmiaceæ.
„ 29. Dipterocarpeæ.
„ 30. Chlænaceæ.

Cohort VI. MALVALES. Sepals valvate. Stamens usually ∞ or monadelphous. Ovary septate, placentæ on the inner angles of the loculi. Endosperm absent or fleshy.

Order 31. Malvaceæ.
„ 32. Sterculiaceae.
„ 33. Tiliaceæ.

Series II. =Discifloræ.= Calyx usually free from the ovary. Petals uniseriate. Stamens usually definite, inserted within, or upon, or around the receptacle, which is more often expanded as a disc. Ovary usually free, or embedded in the disc.

Cohort VII. GERANIALES. Disc usually as a ring between the stamens, or adnate to the staminal tube, or reduced to glands alternating with the petals, more rarely absent. Gynœceum entire, or more often lobed, or sub-apocarpous. Ovules most often 1–2 in each loculus, _pendulous_, _raphe ventral_. Leaves various.

Order 34. Lineæ.
„ 35. Humiriaceæ.
„ 36. Malpighiaceæ.
„ 37. Zygophylleæ.
„ 38. Geraniaceæ.
„ 39. Rutaceæ.
„ 40. Simarubeæ.
„ 41. Ochnaceæ.
„ 42. Burseraceæ.
„ 43. Meliaceæ.
„ 44. Chailletiaceæ.

Cohort VIII. OLACALES. Disc cupular or annular, free, or bearing the stamens and petals on its edge. Gynœceum entire. Ovules 1–3 in the unilocular ovaries, or 1–2 in each loculus, _pendulous_, _raphe dorsal_. Leaves simple.

Order 45. Olacineæ.
„ 46. Ilicineæ.

Cohort IX. CELASTRALES. Disc tumid, adnate to the calyx, or covering its base. Stamens inserted round the disc or affixed to its margin. Gynœceum usually entire. Ovules most often two in each loculus, _erect_, _raphe ventral_. Leaves simple, or rarely compound.

Order 47. Celastrineæ.
„ 48. Stackhousieæ.
„ 49. Rhamneæ.
„ 50. Ampelideæ.

Cohort X. SAPINDALES. Disc various. Stamens variously inserted on the disc. Gynœceum entire, or more often lobed, or sub-apocarpous. Ovules more often 1–2 in each loculus, _ascending_ with _ventral_ raphe, or reversed, or _solitary_ and _pendulous from an ascending funicle_, or rarely ∞ horizontal. Leaves pinnate, or more rarely simple or digitate.

Order 51. Sapindaceæ.
„ 52. Sabiaceæ.
„ 53. Anacardiaceæ.

Anomalous orders, or rather genera,--

Order 54. Coriarieæ.
„ 55. Moringeæ.

Series III. =Calycifloræ.= Calyx-tube usually surrounding the ovary, or adnate to it. Petals uniseriate, inserted on the calyx-tube. Stamens ∞ or definite, inserted on the calyx-tube, or most often on the disc lining the calyx-tube. Ovary often enclosed by the calyx-tube, or inferior.

Cohort XI. ROSALES. Carpels solitary, or free, or united at the base, more rarely at the apex; styles distinct, or very rarely united into a column, and easily separated.

Order 56. Connaraceæ.
„ 57. Leguminosæ.
„ 58. Rosaceæ.
„ 59. Saxifrageæ.
„ 60. Crassulaceæ.
„ 61. Droseraceæ.
„ 62. Hamamelideæ.
„ 63. Bruniaceæ.
„ 64. Halorageæ.

Cohort XII. MYRTALES. Ovary syncarpous, inferior, or enclosed in the calyx-tube, usually divided into loculi; style undivided. Ovules 2–∞ in the loculi.

Order 65. Rhizophoreæ.
„ 66. Combretaceæ.
„ 67. Myrtaceæ.
„ 68. Melastomaceæ.
„ 69. Lythrarieæ.
„ 70. Onagrarieæ.

Cohort XIII. PASSIFLORALES. Ovary syncarpous, inferior or superior, enclosed in the calyx-tube or exserted, unilocular with parietal placentation, or divided into loculi; styles distinct, one style divided, or undivided.

Order 71. Samydaceæ.
„ 72. Loaseæ.
„ 73. Turneraceæ.
„ 74. Passifloreæ.
„ 75. Cucurbitaceæ.
„ 76. Begoniaceæ.
„ 77. Datisceæ.

Cohort XIV. FICOIDALES. Ovary syncarpous, inferior or superior, divided into loculi with sub-basilar placentæ, or more rarely unilocular with parietal placentæ. Styles distinct, or divided at the apex. Embryo curved or excentric.

Order 78. Cacteæ.
„ 79. Ficoideæ.

Cohort XV. UMBRELLALES. Ovary syncarpous, inferior, crowned by the disc, divided into loculi, or unicarpellate. Styles distinct or divided at the apex. Ovules solitary and pendulous in the loculi.

Order 80. Umbelliferæ.
„ 81. Araliaceæ.
„ 82. Cornaceæ.