Part 17 (2/2)

CHAPTER XVIII

CLassIFICATION OF DICOTYLEDONS

DIVISION I--_Choripetalae_

Nearly all of the dicotyledons uished by the character of the petals In the first group, called _Choripetalae_, the petals are separate, or in soenerate forroup, we may select the buttercup, rose, pink, and roup (_Sympetalae_ or _Gamopetalae_) comprises those dicotyledons whose flowers have the petals more or less completely united into a tube The honeysuckles, mints, huckleberry, lilac, etc, are familiar representatives of the _Syhest of all plants

[Illustration: FIG 96--Iuliflorae _A_, male; _B_, female inflorescence of a , _Salix_ (_Ale male flower, 2 _D_, a female flower, 2 _E_, cross-section of the ovary, 8 _F_, an opening fruit _G_, single seed with its hairy appendage, 2]

The _Choripetalae_twenty-two orders The first group is called _Iuliflorae_, and contains numerous, familiar plants, mostly trees In these plants, the flowers are small and inconspicuous, and usually crowded into dense catkins, as in s (Fig 96) and poplars, or in spikes or heads, as in the lizard-tail (Fig 97, _G_), or hop (Fig 97, _I_) The individual flowers are very synciu almost always in separate flowers The outer leaves of the flower (sepals and petals) are either entirely wanting or much reduced, and never differentiated into calyx and corolla

[Illustration: FIG 97--Types of _Iuliflorae_ _A_, branch of hazel, _Corylus_ (_Cupuliferae_), 1 ?, le male flower, 3 _C_, section of the ovary of a female flower, 25 _D_, acorn of red oak, _Quercus_ (_Cupuliferae_),

_E_, seed of white birch, _Betula_ (_Betulaceae_), 3 _F_, fruit of horn-bean, _Carpinus_ (_Cupuliferae_), 1 G, lizard-tail, _Saururus_ (_Saurureae_),_H_, a single flower, 2 _I_, female inflorescence of the hop, _Hule scale with two flowers, 1 _K_, a male flower of a nettle, _Urtica_ (_Urticaceae_), 5]

In the s (Fig 96) the staht-colored, so that the flowers are quite showy, and attract numerous insects which visit them for pollen and nectar, and serve to carry the pollen to the pistillate flowers, thus insuring their fertilization In the roup, however, the flowers are wind-fertilized An excellent exa 97, _A_) Thecatkins at the ends of the branches, shedding the pollen in early spring before the leaves unfold The female flowers are produced on the same branches, but lower down, and in , and covered with minute hairs that catch the pollen which is shaken out in clouds every time the plant is shaken by the wind, and falls in a shower over the stigement is seen in the oaks, hickories, and walnuts

There are three orders of the _Iuliflorae_: _Amentaceae_, _Piperineae_, and _Urticinae_ The first contains the birches (_Betulaceae_); oaks, beeches, hazels, etc (_Cupuliferae_); walnuts and hickories (_Juglandeae_); s and poplars (_Salicaceae_) They are all trees or shrubs; the fruit is often a nut, and the e it

The _Piperineae_ are mostly tropical plants, and include the pepper plant (_Piper_), as well as other plants with similar properties Of our native forms, the only common one is the lizard-tail (_Saururus_), not uncoround In these plants, the calyx and corolla are entirely absent, but the flowers have both carpels and sta our common plants, the nettle family (_Urticaceae_); plane family (_Plataneae_), represented by the sycamore or buttonwood (_Platanus_); the hemp family (_Cannabineae_); and the elm family (_Ulmaceae_) The flowers usually have a calyx, and may have only stamens or carpels, or both So the flowersa fruit-like structure Well-known exaroup of the _Choripetalae_ is called _Centrosper seven faineae_), are represented by numerous native species

The latter coardens by the showy ”four-o'clock” (_Mirabilis_) In this plant, as in most of the order, the corolla is absent, but here the calyx is large and brightly colored, reselory or petunia The stamens are usually h cole cavity with the ovules arising froh sometimes the ovary is several celled

[Illustration: FIG 98--Types of _Centrosper-beauty, _Claytonia_ (_Portulacaceae_),_B_, a single flower, 1 _C_, fruit, with the sepals re the curved eonuonaceae_), 2 _F_, the pistil, 2

_G_, section of the ovary, showing the single ovule, 4 _H_, section of the seed, 2 _I_, base of the leaf, showing the sheath, 1 _J_, flower of pig-weed, _Chenopodium_ (_Chenopodiaceae_), 3: i, from without; ii, in section _K_, flower of the poke-weed, _Phytolacca_ (_Phytolaccaceae_), 2 _L_, fire-pink, _Silene_ (_Caryophyllaceae_),_M_, a floith half of the calyx and corolla removed, 1

_N_, ripe fruit ofby ten teeth at the suraoneae_) is represented by the various species of _Polygonu cultivated plants by the buckwheat (_fagopyru native plants, and the beet and spinach of the gardens are exa the last is the amaranth family (_Amarantaceae_), of which the showy areen a-weed are representatives

The poke-weed (_Phytolacca_) (Fig 98, _K_), so conspicuous in autumn on account of its dark-purple clusters of berries and crimson stalks, is our only representative of the fahest families are the purslane family (_Portulacaceae_) and pink family (_Caryophylleae_) These are e and conspicuous, though so_ some chick-weeds, have no petals Of the purslane faardens, and the co-beauty (_Claytonia_) (Fig 98, _A_) are the commonest examples The pink family is represented by many common and often showy plants The carnation, japanese pinks, and silliaenus _Dianthus_, of which there are also two or three native species, are aenera _Lychnis_ and _Silene_ (Fig 98, _L_) also contain very showy species

Of the less conspicuous genera, the chick-weeds (_Cerastiuroup of the _Choripetalae_ (the _Aphanocyclae_) is a very large one and includesfive orders The lower ones have all the parts of the flower entirely separate, and often indefinite in nuyncium composed of two or more carpels united to form a compound pistil

The first order (_Polycarpae_) includes ten families, of which the buttercup family (_Ranunculaceae_) is the most familiar The plants of this family show much variation in the details of the flowers, which are usually showy, but the general plan is99, _A_), clematis, and others, the corolla is absent, but the sepals are large and brightly colored so as to appear like petals In the colu 99, _F_) the petals are tubular, for 99, _T_) one of the sepals is si the custard-apple family (_Anonaceae_) is the curious papaw (_Asi 100, _A_) The family is mainly a tropical one, but this species extends as far north as southern Michigan

[Illustration: FIG 99--Types of _Aphanocyclae_ (_Polycarpae_), family _Ranunculaceae_ _A_, Rue anemone (_Anemonilla_),_B_, a fruit, 2 _C_, section of the same _D_, section of a buttercup flower (_Ranunculus_), 1 _E_, diagraia_),_G_, one of the spur-shaped petals, 1