Part 49

=a.= =5-stamened.=--_Verbascum_ (Mullein, Fig. 563 _A_) has a slightly irregular, rotate corolla; five stamens (frequently covered with woolly hairs), of which the two anterior ones are the longer and differ often also in other respects. ~The inflorescences are racemose, often with several series of accessory dichasia in the axil of each primary floral-leaf. The leaves are scattered and, together with the stems, are often covered with a grey felt of branched hairs.~

=b.= =4-stamened, didynamous= (Fig. 564).--_Scrophularia_ (Fig-wort, Fig. 565) has cymose inflorescences in a panicle; the corolla (Fig. 565) is urceolate, short two-lipped; the posterior stamens are present as a scale below the upper lip of the corolla (Fig 565 _s_). ~_S. nodosa_ has a tuberous rhizome.--_Pentstemon_; the posterior stamen is barren and very long.~--_Antirrhinum_ (Snapdragon). The corolla (Fig. 564) is personate, _i.e._ bilabiate, but with the under lip arched to such an extent that it meets the upper lip, closes the corolla throat, and entirely conceals the stamens and style; the corolla-tube is produced into a short pouch at the base on the anterior side. The capsule is oblique and opens by 2–3 pores, formed by small, dentate valves. In _Linaria_ (Toad-flax) the pouch is produced into a spur. Sometimes there are traces of the posterior stamens. The capsule opens by large pores (one for each loculus), produced by large, many-partite valves. _L. vulgaris_ reproduces by suckers.--_Digitalis_ (Foxglove, Fig. 566) has long racemes with drooping flowers; the posterior sepal is small (a step towards complete suppression, as in _Veronica_); the corolla is obliquely campanulate, and generally nearly 4-lobed, the two posterior petals coalescing.--_Alonsoa_; _Nemesia_; _Chelone_; _Herpestis_; _Mimulus_; _Torenia_; _Vandellia_; _Limosella_ (_L. aquatica_, Mud-wort, native); _Scoparia_; _Capraria_; _Erinus_ (found on the Roman Camp at Chesters, Northumberland, and supposed to have been introduced from Spain by the Roman soldiers); _Celsia_ (near _Verbascum_); _Maurandia_; _Lophospermum_; _Rhodochiton_; _Collinsia_; _Nycterinia_, etc.

=c.= =2-stamened.=--_Gratiola_ (Water-hyssop). 5-partite calyx. The upper lip of the corolla is undivided or slightly bifid; the two anterior stamens are either entirely absent or are reduced to staminodes (a transition to _Veronica_).--_Veronica_ (Speedwell), most frequently 4-partite calyx; 4-lobed, rotate, zygomorphic corolla with 2 perfect stamens and no trace of the others (Figs. 567, 562 _c_); capsule with loculicidal dehiscence. _Calceolaria_; the corolla has two slipper-like lips.

=2.= RHINANTHEÆ, YELLOW-RATTLE GROUP. Herbs, all of which (with the exception of _Lathræa_) are annual _parasites_ with green foliage-leaves. They attach themselves by haustoria to the roots of other plants and draw nourishment from them. The majority turn black when dried. Racemose inflorescences. In many the calyx is 4-partite, the posterior sepal being absent, or very small. The corolla is distinctly bilabiate (Fig. 568), with _most frequently ascending æstiration_; in the majority it does not become detached at the base, but by means of a ring-like cut some distance up the tube; 4 didynamous stamens; pollen-grains dry, easily falling out; the anthers are often furnished at the base with bristles or hairs (Fig. 568) which play a part in the pollination, the probosces of the insects, being forcibly pushed against them, agitate the anthers and shake out the pollen-grains. Capsule with loculicidal dehiscence.--_Euphrasia_ (Eye-bright), _Melampyrum_ (Cow-wheat), _Rhinanthus_ (Yellow-rattle), _Odontites_ (Bartsia), _Pedicularis_ (Louse-wort), and _Lathrœa_ (Tooth-wort) all have native species. The last named is pale yellow, or reddish (without chlorophyll); ~it is a parasite on the roots of the Hazel, Beech and other shrubs, having an aerial stem, and an underground, perennial rhizome, covered with opposite, scale-like, more or less fleshy leaves with a number of internal glandular, labyrinthine cavities. The inflorescence is a unilateral raceme. It approaches _Gesneriaceæ_ in having a _unilocular_ ovary with two parietal placentæ.~

The mechanical contrivances for POLLINATION are so numerous that no general principle can be laid down. Personate flowers, like those of _Antirrhinum_ are only accessible to strong insects, such as humble-bees, which can force themselves between the two lips, and so become dusted with pollen on the back. In _Euphrasia_ and other _Rhinantheæ_ the insects become covered with smooth, powdery pollen when they shake the anther-apparatus in touching the hairs and bristles mentioned above. _Scrophularia nodosa_ is protogynous (Fig. 565). _Digitalis purpurea_, however, is protandrous. _Mimulus luteus_ and some others have sensitive stigmatic lobes, which shut up on being touched. The _Veronica_-species constitute a series, from large-flowered down to small-flowered forms, and parallel with them are found various gradations from insect-to self-pollination. In some (as _Euphrasia officinalis_, _Rhinanthus crista galli_) there are two kinds of flowers: large, which are pollinated by insects, and small, which are self-pollinated (Fig. 568). _Lathræa squamaria_ (Tooth-wort) is a protogynous spring-flowering plant, largely visited by humble-bees. Others have cleistogamic flowers. _Nycterinia capensis_ opens its flowers at night.

2,000 species; chiefly from the Temp. OFFICINAL: _Digitalis purpurea_ (the leaves; Europe), a poisonous plant. _Verbascum thapsus_ and _thapsiforme_, _Veronica officinalis_ (“Herba V.”), _Gratiola officinalis_ (“Herba”) have medicinal uses. The whole of the Scrophulariaceæ are more or less suspicious, if not actually poisonous, and none serve as food. Many are ORNAMENTAL PLANTS: _Mimulus luteus_ (N. America), _Paulownia imperialis_ (the only species; in Japan; a tree), _Antirrhinum vulgare_ (S. Eur.), _Linaria_, _Pentstemon_, _Veronica_, _Calceolaria_ (Peru, Chili, etc.).

Order 4. =Utriculariaceæ.= To this order belong only perennial, _insectivorous_, _aquatic_, and _marsh-plants_ (200 species) with a more or less characteristic appearance. They differ from the Scrophulariaceæ, especially in having =2= stamens (the anterior) and a _unilocular ovary_, with _free, central placenta_ (like that of the Primulaceæ). For the rest the flower is distinctly bilabiate, both in the calyx and corolla. Two-valved capsule; no endosperm.

_Pinguicula_ (Butter-wort) has a rosette of leaves close to the ground; these are sticky, covered with glandular hairs, and roll round any small insects which may be caught upon them; flowers solitary, terminal on a long scape; calyx, 5-partite; corolla with spur. The embryo germinates with 1 cotyledon.--_Utricularia_ (Bladder-wort). Our native species are floating, _without roots_, with hair-like, divided leaves, studded with peculiar bladders (in the Tropics there are terrestrial species, with ordinary foliage). The bladders (Fig. 569) have an aperture, closed by a valve opening inwards, so that small aquatic animals are allowed to enter, but are not able to escape; they are thus entrapped in the bladders, and are probably used as food. Calyx bipartite; corolla personate with spur.

The _embryo_ of _Utricularia_ is very imperfect, scarcely more than a spherical, cellular mass, with a few slight leaf-rudiments. On the germination of _U. vulgaris_, several bristle-like leaves develop into a compact rosette; the stem then develops, and also the finely-divided, bladder-bearing leaves. A primary root is not developed. The stems branch copiously and in a very peculiar manner. The growing-point of the stem is rolled spirally.--The stigmatic lobes are sensitive and close on being touched; self-pollination often takes place, however, in _Pinguicula_.

Order 5. =Gesneriaceæ.= The flower in this order may be both _epigynous_ (_Gesnerieæ_) and _hypogynous_ (_Cyrtandreæ_), but otherwise is nearly the same as in Scrophulariaceæ, only that _the ovary is unilocular_, with 2 _parietal_, often bifid, _placentæ_. Of the 5 stamens the posterior is rudimentary, or (more rarely) entirely wanting, and the others are didynamous (Cyrtandreæ have often only 2 stamens); their anthers are generally glued into a quadrangular mass. The majority are herbs with juicy stems, opposite, verticillate or scattered leaves without stipules, often, like the stems, thick and juicy, soft-haired or glabrous. The corollas are often highly-coloured (scarlet, red-yellow, etc., and spotted internally), large and magnificent, so that many species are ornamental plants. GESNERIEÆ (often epigynous) have endosperm; S. Am.--CYRTANDREÆ, hypogynous, without endosperm; Asia, S. Africa.--_Streptocarpus_, neither the primary root nor primary shoot attains development; one of the cotyledons dies, while the other grows and becomes a very large foliage-leaf, from which spring adventitious roots and adventitious inflorescences.

500 species. _Gloxinia_, _Achimenes_, _Gesneria_, _Alloplectus_, _Tydæa_, _Columnea_, _Nægelia_, _Æschynanthus_, and others, especially in the forests of tropical America. Some are epiphytes on trees, others prefer the leaf-mould of the forest and crevices of cliffs. Several genera have peculiar, catkin-like, underground shoots, with scale-like compact leaves; others have tubers.

_Orobanche_ (Broom-rape) is allied to this order as a _parasitic_ form. It is a parasite on the roots of other plants, not like _Lathræa_ by means of thin rootbranches with haustoria, but growing with the base of its stem in close contact with its host, and probably even often protruding a kind of thallus into it, in a manner similar to the Loranthaceæ. Its aerial shoots are not entirely destitute of chlorophyll, but are not green; they only bear scale-leaves and terminate in a raceme or spike-like inflorescence.--Some _Orobanche_-species are detrimental to various cultivated plants (Hemp, Lucerne, Tobacco, etc.). The flowers are strongly zygomorphic; the posterior sepal is often wanting, and the anterior are united to the two lateral ones. Ovary unilocular, as in Gesneraceæ, with 2 or 4 parietal placentæ.--The exceedingly small seeds have a very rudimentary embryo, formed of an ellipsoidal, cellular mass, without indication of cotyledons or other organs.--About 100 species; especially in the Mediterranean region.

Order 6. =Bignoniaceæ.= 500 species; nearly all trees and shrubs, and to a great extent lianes, climbing by tendrils (modified leaves), which are sometimes terminated by a special clasping apparatus. These lianes have, as a rule, an _anomalous stem structure_, the wood being either divided into four wedges at right angles to each other, separated by four grooves filled with secondary wood-parenchyma, or a greater number of wedges occur, by the cambium ceasing to form wood in several places. The leaves are most frequently opposite and compound; the flowers in the main are similar to the didynamous Scrophulariaceæ, and especially resemble those of _Digitalis purpurea_; they are bilabiate, large, and beautiful, campanulate or trumpet-shaped, many of the prettiest ornamental plants in the Tropics belonging to this order. The fruit is most frequently a large, woody, 2-valved, siliqua-like, septifragal capsule, whose valves separate from the flat and broad partition-wall, which bears the large, generally winged seeds: _Tecoma_; _Bignonia_.--In gardens: _Catalpa syringæfolia_ (Trumpet-wood); _Tecoma radicans_ (from S. Am.).--“Palisander”-wood is from _Jacaranda_ (S. Am.).--_Eccremocarpus_ (N. Am.) forms, by its unilocular capsule, a transition to the Gesneriaceæ (_E. scaber_; herbaceous).

_Crescentia_ is allied to this order; _C. cujete_ (Calabash) is its best known species. The fruit (unilocular with 2 parietal placentæ) is a very large, spherical or ellipsoidal berry, with a firm, finally woody outer layer. After the removal of the juicy interior, these are commonly used as drinking vessels in Tropical America.

Order 7. =Pedaliaceæ.= _Sesamum_ (_orientale_ and _indicum_); very important oil-plants, which from olden times have been cultivated in tropical Asia and Africa for food and as medicinal plants, and are now cultivated in America also. The seeds are used as a raw material in the manufacture of soap in Europe.--To this order also belong _Martynia_ and _Craniolaria_, which have a long horned capsule and sensitive stigmas.--46 species.

Order 8. =Acanthaceæ.= 1,500 species; mostly erect, slender, branched herbs or shrubs, rarely arborescent, especially in S. Am. and Ind. The branches frequently have swollen nodes; the leaves are _opposite_, penninerved, undivided, more or less lanceolate or elliptical, and generally leave a distinct scar when they fall off. Stipules are wanting. The flowers are solitary or in dichasia, which are arranged in 4-rowed spikes or racemes, each flower with its subtending bract, which may be brightly coloured, and most frequently also with two bracteoles. With regard to the corolla (which is often labiate, in any case irregular, and frequently prettily coloured), the 2 or 4 didynamous stamens (of whose anthers one half is inserted lower than the other, or suppressed) and the gynœceum, the Acanthaceæ are true Personatæ, approaching most nearly to the Scrophulariaceæ: they differ from the other orders especially in the _fruit_, which is a bilocular, 2-valved, often elastically dehiscing capsule, which never has more than 2 rows, and in some only 2 seeds in each loculus, the seeds being often compressed and borne on _strong_, _curved_ or _hook-like funicles_ (_retinacula_) which persist after dehiscence. _Embryo curved without endosperm_; radicle pointed downwards.--Cleistogamic flowers are found in several species. Cystoliths are common.

The following grow wild in Europe: _Acanthus_ (_spinosus_ and _mollis_, whose pinnatifid leaves served as models for the capitals of the Corinthian columns). The posterior sepal is the largest of all the leaves of the flower, and covers the other parts like a helmet; the 2 anterior sepals are united, and the two lateral ones are small and greenish; the corolla has no upper-lip, but only a 3-lobed under-lip. The anthers are bilocular; the filaments ultimately become very firm.--_Justicia_, _Eranthemum_, _Goldfussia_, _Thunbergia_ (a twiner), _Ruellia_, _Dicliptera_, etc.--Ornamental plants in conservatories.

Order 9. =Plantaginaceæ= (=Plantains=). The flowers (Figs. 570, 571) are regular, ☿, hypogynous, with a =4=-partite, persistent calyx, a gamopetalous, _scarious_ corolla with =4= projecting lobes, =4= stamens, incurved in the bud, later on projecting considerably, about equal in length, and a bilocular ovary with _one_ long, filamentous, _undivided_, _feathery_, papillose style (see Fig. 571). The ovary is most frequently bilocular with 1–few ovules in each loculus. An hypogynous disc is wanting. The fruit is a _pyxidium_ with 1–few peltate seeds attached in each loculus (_Littorella_ is in several respects an exception). All species are herbs, the majority with leaf-rosettes near the ground, and the flowers in spikes or capitula.

The labiate-like flowers are in this case entirely concealed under a regular, apparently 4-merous exterior. The structure of the flower, however, is the same as in the _Scrophulariaceæ_, only the reduction, which is found in _Veronica_ (compare Figs. 562 _C_, 567 with 570, 571), is also present in this instance and the lobes are also more equally developed; the posterior petal corresponds to the bilobed upper-lip; the posterior stamen and the posterior sepal also are entirely wanting. In the development of the flower there is no trace of posterior sepal or stamen, and the posterior petal arises from one primordium, but the two anterior sepals arise before the lateral ones. The position of sepals and petals does not agree with that of a true 4-merous flower, which is represented in Fig. 361 _E._ The bracteoles are always suppressed in _Plantago_.

_Plantago_ (Plantain, Rib-grass). The foliage-leaves are most frequently scattered, entire, with curved veins, arranged in a rosette close to the ground on an unlimited rhizome; the spike-like inflorescence is borne on a long scape; in some (_P. psyllium_) the leaves are opposite on a stem with well-developed internodes, and the inflorescences are borne in their axils. The order also presents a transition from insect-pollinated to wind-pollinated flowers. ~The flowers are protogynous, wind-pollinated in _P. major_ and _P. lanceolata_, partly also in the other species, but insect pollination also occurs, and _P. media_ has three kinds of flowers, some of which are adapted for wind-pollination (Fig. 571), others, with short filaments, for insects.~ _Littorella lacustris_ (Shore-weed) is the most reduced of the Plantaginaceæ: an aquatic plant with rosettes of round, awl-like leaves and diclinous (monœcious) flowers. ~In the axils of the foliage-leaves is a very short 3-flowered spike, formed by 2 sessile ♀-flowers, and above them a long-stalked ♂-flower; all the flowers are lateral, the terminal one being absent, as in _Plantago_. The ♂-flower is essentially the same as in _Plantago_, but the ♀-flower has a scarious corolla, with a narrow, 3–4-dentate mouth, which closes tightly round the nut-like fruit.~

The genus _Plantago_ constitutes nearly the entire order (200 species). Some are widely distributed weeds (_e.g._ _P. major_, “The white man’s footstep”). In _P. psyllium_ (S. Eur.) the integument of the seeds is mucilaginous, and swells considerably in water.

Family 31. =Nuculiferæ.=

The flowers are _hypogynous_ and _zygomorphic_ (in _Boraginaceæ_ and _Cordiaceæ_, however, they are regular, except _Echium_ and _Anchusa arvensis_). The calyx is gamosepalous, the corolla _bilabiate_ (except in the two orders mentioned), mostly after 2/3, _i.e._ divided into a 2-leaved posterior portion, and a 3-leaved anterior portion. The æstivation of the corolla is nearly always descending.--In _Boraginaceæ_ and _Cordiaceæ_ there are 5 stamens of equal length; in the other orders 4 didynamous ones, or only 2 fertile; the posterior stamen is sometimes developed as a staminode, sometimes fertile (in _Stilbaceæ_). The ovary is formed of 2 median carpels (except some _Verbenaceæ_), with (1-) =2= ovules on each carpel; in the majority of the orders it is, however, divided by a false partition-wall between the dorsal and ventral sutures, into =4= _loculi_, each of which is often raised independently, causing the style to be situated in the depression between the four lobes (“gynobasic” style, Figs. 572, 573, 575, 579). The fruit in these orders most frequently becomes a _4-partite schizocarp_ with _nut-like fruitlets_. The other orders have a 1(-2)-locular ovary.--The leaves are _simple, without stipules_.

The family is related to (and proceeds from) the _Tubifloræ_, especially _Convolvulaceæ_, which has an almost similar construction of the ovary. It is doubtful whether the _Cordiaceæ_ and _Boraginaceæ_ should be classed with the others.

The orders are: 1, Cordiaceæ; 2. Boraginaceæ; 3, Verbenaceæ; 4, Labiatæ; 5, Selaginaceæ; 6. Globulariaceæ; 7, Stilbaceæ.

Order 1. =Cordiaceæ= unites Convolvulaceæ and Boraginaceæ. Tree-like plants with 5-(4–10) merous flowers, doubly bifid style, and drupe with 4 or less loculi. No endosperm; cotyledons folded.--185 species; tropical.

Order 2. =Boraginaceæ.= The vegetative parts are very characteristic: _herbs_ with _cylindrical_ stems and _scattered_, undivided, nearly always sessile, entire leaves, without stipules, and generally, together with the other green portions of the plant, covered with stiff hairs, consequently rough and often even stinging (hence the other name for the order _Asperifoliæ_). The inflorescences are _unipared scorpioid cymes_ with the branches coiled spirally (“helicoid,” Fig. 573) before the flowers open. The flower is perfect, _regular_ (obliquely zygomorphic in _Echium_ and _Anchusa arvensis_), hypogynous, gamopetalous: S5, P5 (often with ligular outgrowths), A5, G2, but each of the two loculi of the ovary becomes divided by a false partition-wall into two, each of which contains one _pendulous_ anatropous ovule with the micropyle turned upwards; the four loculi arch upwards, so that the ovary becomes 4-lobed, and the style is then, as in the _Borageæ_, placed _at the base_ (“gynobasic”) between the four projections (Figs. 572, 573). The fruit is a _4-partite schizocarp_ with four nut-like fruitlets (Fig. 572).--_Endosperm is wanting_ (except in _Heliotropium_); the radicle is turned _upwards_.

The INFLORESCENCES are often double unipared scorpioid cymes; the bud of the second bracteole is developed, that of the first suppressed; in some cases both the bracteoles are suppressed (_Myosotis_, _Omphalodes_, etc.), but in other instances all the first bracteoles (_a_) only are suppressed, and the others are then situated in two rows towards the under side of the coiled axis, while the flowers are situated on the upper side. Displacement of the branches or of the floral-leaves sometimes takes place. The flowers are often red at first, and later on become blue or violet; they hardly ever have any smell. The fruit entirely resembles that of the Labiatæ, but the radicle of the latter is turned downwards. The fruitlets present small differences which have systematic importance; they are hollow or flat at the base, attached to a flat or columnar receptacle, etc.

=1.= HELIOTROPIEÆ. This group deviates from the characteristics mentioned above in the undivided ovary and terminal (“apical”) style. In this, as well as in the fact that in some genera (_Tournefortia_, _Ehretia_, etc.) the fruit is a drupe, it connects this order with the Cordiaceæ. _Heliotropium_, _Tiaridium_, and others have schizocarps.

=2.= BORAGEÆ, BORAGE GROUP. Style gynobasic; fruit a schizocarp.