[Illustration: FIG. 109.--_Eucylæ_ (_Frangulinæ_), _Tricoccæ_. _A_, flowers of spindle-tree, _Euonymus_, (_Celastraceæ_), × 1. _B_, cross-section of the ovary, × 2. _C_, diagram of the flower. _D_, leaf and fruit of bitter-sweet (_Celastrus_), × ½. _E_, fruit opening and disclosing the seeds. _F_, section of a nearly ripe fruit, showing the seeds surrounded by the scarlet integument (aril). _em._ the embryo, × 1. _G_, flower of grape-vine, _Vitis_ (_Vitaceæ_), × 2. The corolla has fallen off. _H_, vertical section of the pistil, × 2. _I_, nearly ripe fruits of the frost-grape, × 1. _J_, cross-section of young fruit, × 2. _K_, a spurge, _Euphorbia_ (_Euphorbiaceæ_), × ½. _L_, single group of flowers, surrounded by the corolla-like involucre, × 3. _M_, section of the same, ♂, male flowers; ♀, female flowers. _N_, a single male flower, × 5. _O_, cross-section of ovary, × 6. _P_, a seed, × 2. _Q_, longitudinal section of the seed, × 3. _em._ embryo.] The fifth group of the _Choripetalæ_ is a small one, comprising but a single order (_Tricoccæ_). The flowers are small and inconspicuous, though sometimes, as in some _Euphorbias_ and the showy _Poinsettia_ of the greenhouses, the leaves or bracts surrounding the inflorescence are conspicuously colored, giving the whole the appearance of a large, showy, single flower. In northern countries the plants are mostly small weeds, of which the various spurges or _Euphorbias_ are the most familiar. These plants (Fig. 109, _K_) have the small flowers surrounded by a cup-shaped involucre (_L_, _M_) so that the whole inflorescence looks like a single flower. In the spurges, as in the other members of the order, the flowers are very simple, being often reduced to a single stamen or pistil (Fig. 109, _M_, _N_). The plants generally abound in a milky juice which is often poisonous. This juice in a number of tropical genera is the source of India-rubber. Some genera like the castor-bean (_Ricinus_) and _Croton_ are cultivated for their large, showy leaves. The water starworts (_Callitriche_), not uncommon in stagnant water, represent the family _Callitrichaceæ_, and the box (_Buxus_) is the type of the _Buxaceæ_. [Illustration: FIG. 110.--Types of _Calycifloræ_ (_Umbellifloræ_). _A_, inflorescence of wild parsnip, _Pastinaca_ (_Umbelliferæ_), × ½. _B_, single flower of the same, × 3. _C_, a leaf, showing the sheathing base, × ¼. _D_, a fruit, × 2. _E_, cross-section of _D_. _F_, part of the inflorescence of spikenard, _Aralia_ (_Araliaceæ_), × 1. _G_, a single flower of the same, × 3. _H_, the fruit, × 2. _I_, cross-section of the _H_. _J_, inflorescence of dogwood, _Cornus_ (_Corneæ_). The cluster of flowers is surrounded by four white bracts (_b_), × ⅓. _K_, a single flower of the same, × 2. _L_, diagram of the flower. _M_, young fruit of another species (_Cornus stolonifera_) (red osier), × 2. _N_, cross-section of _M_.]