Part 48

_Primula_ (Primrose) has most frequently a vertical rhizome, bearing a rosette of leaves at its summit, and long-stalked umbels; corolla _rotate_ or slightly funnel-shaped; the capsule opens at the apex by 5 _teeth_. The flowers in some species are heterostyled (long-styled or short-styled; Fig. 548). Closely allied are _Androsace_ (with ovate, cup-shaped corolla-tube and ligular scales, alternating with the corolla-lobes) and _Soldanella_ (funnel-shaped corolla with laciniate lobes and most frequently ligular scales).--_Hottonia_ (Water-Violet) is an aquatic plant with pectinate leaves and heterostyled flowers.--_Cortusa._ _Dodecatheon._ _Cyclamen_ (Fig. 549) has solitary, long-stalked flowers, and a rotate corolla with the lobes reflexed; the stalk of the capsule rolls up spirally; the tuberous rhizome is formed by the hypocotyledonary internode. Only 1 cotyledon.--_Lysimachia_ (Money-wort); stem-internodes well developed, leaves opposite or verticillate, calyx almost polysepalous, corolla deeply 5-partite (Fig. 550). The flowers are solitary or in racemes.--_Anagallis_ (Pimpernel), leaves opposite, flowers solitary; the fruit a pyxidium (Fig. 551); similarly in _Centunculus_, which is 4-merous.--_Trientalis_, the flowers are most frequently 7-merous.--_Glaux_ (Sea Milk-wort) is a creeping maritime plant with opposite leaves; flowers solitary in the leaf-axils, _corolla absent_, but with coloured calyx. ~The petals are usually developed later than the stamens in the Primulaceæ; but in this instance they are entirely suppressed.~--_Samolus_ (Brookweed) differs from all the others in having an _epigynous_ flower; barren sepal-stamens are also present. The bracts in the racemose inflorescences are displaced along the flower-stalks.

POLLINATION. Insect-pollination in the majority; cross-pollination is promoted in some by heterostyly (Fig. 548).--300 species; especially in northern temperate zones; the majority on mountains (_Soldanella_, _Androsace_, etc.); almost absent in the Tropics. A large number are ORNAMENTAL PLANTS, _e.g._ _Primula auricula_ (from the Alps), _P. sinensis_ (China), _P. elatior_ (Oxslip, a native) and _grandiflora_, etc. _Cyclamen europæum_ (Alpine Violet); the tubers are poisonous.

Order 2. =Myrsinaceæ.= Trees or shrubs; evergreen, tropical Primulaceæ with fleshy fruits and few seeds, embedded in the placenta. The leaves are nearly always dotted with yellow glands (schizogenous resin-receptacles).--550 species; especially Am.--ORNAMENTAL PLANTS: _Ardisia crenulata_ (W. Ind.); other genera: _Clavija_, _Maesa_, _Theophrasta_ (barren sepal-stamens), _Myrsine_, _Jacquinia_ (barren sepal-stamens), etc.--_Ægiceras_, allied to this order, comprises arborescent plants, often growing with _Rhizophora_ in tropical forests, along the shore. The embryo germinates while still in the fruit.

Order 3. =Plumbaginaceæ.= This order has a position of the stamens similar to that in Primulaceæ (S5, P5, A0 + 5, G5), but it differs from these in the flower, which has generally a _membranous_, dry, thin, coloured, folded, almost entire calyx and an _almost entirely polypetalous corolla_, which, as a rule, has twisted æstivation and is _only united_ with the stamens _at its base_; but more especially it differs in the ovary, which bears 5 _free_ or almost free _styles_ and only 1 _basal_ ovule with a _long_, twisted funicle (the placenta of the Primulaceæ is here so much reduced that it bears only 1 ovule). The fruit is a _nut_ or _capsule_. The radicle is turned outwards. Endosperm mealy.--To this order belong herbs or under-shrubs, which are especially natives of the sea-coast and of salt-steppes; they also resemble the Primulaceæ in the scattered, undivided, entire leaves (without stipules), often in rosettes, and the inflorescence borne on a long stalk. In opposition to the Primulaceæ, the _bracteoles are typically present, and hence the branching is generally cymose_ (scorpioid).

_Armeria_ (Thrift) has a round _capitulum_, composed of closely-packed dichasia, surrounded at its base by an involucre with peculiar prolongations, directed downwards, and united into a sheath protecting the intercalary zone of growth. The pericarp is finally ruptured at the base, and drops off like a hood.--In _Statice_ (Sea-lavender), the unipared scorpioid cymes are prolonged and collected into panicle-like inflorescences.--~_Plumbago_ is the genus which approaches nearest to the Primulaceæ, and differs most from the characters given above. It has capitate or spike-like inflorescences, a salver-shaped corolla, and the stamens are not attached to the corolla. The style is only divided at the extremity; the calyx is not membranous, but is covered with sticky, glandular hairs.~

250 species; chiefly in the Mediterranean and about the Caspian Sea, on salt-steppes and beaches. Some are Tropical; a few are ornamental plants.

B. Tetracyclicæ.

a. Tetracyclicæ with hypogynous flowers.

Family 29. =Tubifloræ.=

The flower is regular, ☿, and _hypogynous_. The gamopetalous type is present in this family with great uniformity, without suppression or splitting; S5, P5, A5, G2 (3–5). The stamens are all fertile, alternating with the lobes of the corolla. Gynœceum with 2, more seldom 3–5 syncarpous carpels. Style nearly always simple; 2 dorsal stigmas. In each carpel 2–∞ ovules. At the base of the ovary is found a yellowish ring-like nectary (Fig. 552 C), sometimes 5-sinuate or 5-partite.--The leaves are nearly always scattered; stipules are absent.--~The Solanaceæ, which formerly were classed here, are so closely allied to the Personatæ, that it would be unnatural not to place them first in this family; and the Boraginaceæ (which were also placed in the Tubifloræ) appear to be best united, with the Labiatæ and others, into one family Nuculiferæ.~

Order 1. =Polemoniaceæ.= The flowers are regular; S5, P5, A5, G3. The calyx and corolla have united leaves, the petals _twisted_ to the right in _æstivation_ (all the left edges being covered). The ovary is 3-locular with 2–∞ ovules in each loculus; the style is trifid at the apex; the fruit is a 3-valved capsule. Embryo straight; endosperm fleshy. The inflorescences are dichasia passing over into unipared helicoid cymes (the shoot of the _lower_ bracteole being the more strongly developed).--Herbs without latex. 150 species; especially Western N. Am.--_Phlox_ (salver-shaped corolla; entire, opposite leaves), _Polemonium_ (campanulate or almost rotate corolla; scattered, pinnate leaves), _Leptosiphon_, _Gilia_, _Collomia_, _Cobæa_ (climbing, like the Vetches, by tendrils at the ends of the leaves), etc. They are frequently ornamental plants.

Order 2. =Hydrophyllaceæ.= This order approaches very closely to the Boraginaceæ. Herbs with pinnate or palmate leaves; S5, P5, A5, G2. The lobes of the corolla are imbricate in æstivation. Generally 2 median carpels. The ovary is _most frequently unilocular_, and the seeds are situated on 2 _parietal placentæ_; capsule 2-valved; embryo straight; endosperm fleshy. In the corolla-tube, opposite the corolla-lobes, there are frequently appendages of various forms, which resemble those of _Cuscuta_. The inflorescences correspond exactly with those of the Boraginaceæ, being _unipared scorpioid cymes_, which, prior to opening, _are tightly rolled up_.--130 species, especially in N. Am. (California, etc.). Many annual species of _Phacelia_, _Nemophila_, _Whitlavia_, _Eutoca_, _Cosmanthus_, etc., are cultivated in gardens as ornamental plants. _Hydrolea_ (has a bilocular ovary, and two free styles).

Order 3. =Convolvulaceæ= (=Bindweeds=). The flower is regular, hypogynous, with 5 almost free sepals (quincuncial æstivation), P5, A5, G2 (rarely 3–5). The _corolla_ is very characteristic; it is (with various forms) almost entire, or slightly 5-lobed, and _folded_ longitudinally _in the bud_ in such a way that 5 projecting, flat portions, tapering towards the top and frequently differing in colour and hairiness from the rest, are visible externally and applied close together, while the remainder of the corolla is folded inwards (Fig. 552 A); and hence the whole corolla is _strongly twisted to the right_ in the bud. The gynœceum most frequently has a bilocular ovary; _in each loculus_ there are _only_ 2 (erect) _anatropous ovules_ on the placenta, which is not especially thickened (Fig. 552 _D_, _E_); each loculus is sometimes divided into two by a false septum (a relationship with the _Boraginaceæ_, etc.); style simple with most frequently a bilobed stigma, or a bipartite style. The fruit is nearly spherical, most frequently a _capsule_. The seeds are erect, and have a large hilum at the base. The embryo is _curved_, with leaf-like, thin, bilobed, most frequently folded cotyledons; _endosperm absent or mucilaginous_.

=1.= CONVOLVULEÆ, BINDWEED GROUP. The majority are _twining_ (to the left) _herbs_, with _latex_. The leaves are scattered, without stipules, often long stalked, and nearly always with cordate base; some are palmately lobed. The flowers are most frequently solitary in the leaf-axils, large, quickly withering.--_Convolvulus_ (Fig. 552), _Calystegia_ (unilocular ovary, 2 large bracteoles), _Ipomœa_, _Batatas_, _Evolvulus_ (with a doubly bifid style), _Calonyction_, _Pharbitis_, etc.

=2.= DICHONDREÆ. This group is a more primitive form, not twining, and without latex. It has 2 _free_ carpels with basal style (as in Boraginaceæ) and valvate corolla.

=3.= CUSCUTEÆ, DODDER GROUP (Fig. 553). Parasites, with round, filamentous stems, bearing only scale-like leaves and almost destitute of chlorophyll (they are reddish or yellowish); they are parasitic upon other plants, around which they twine, first with narrow, compact coils from which haustoria (Fig. 553 _A_) are developed which enter the host-plant, and then with wider coils by which they raise themselves to other portions of their host or try to reach other plants. On germination a very temporary primary root is developed, which bears root-hairs as far as the tip (rootcap is wanting); it only serves as a kind of reservoir for water, and perishes very soon after the seedling has fastened on to a host. The embryo is filamentous and rolled up _spirally_ (Fig. 553 _C_), and is sometimes destitute of cotyledons. The flowers are crowded into capitulate inflorescences, complicated by accessory shoots (Fig. 553 _A_); they have S5, P5 (_imbricate_ æstivation), A5 (and beneath the stamens 5 scales on the corolla-tube), G2. Fruit a capsule opening by a lid.--_Cuscuta europœa_, _C. epilinum_ (Flax-Dodder), _C. epithymum_ (Lesser-Dodder), _C. trifolii_ (Clover-Dodder), etc., are parasitic on different hosts, or parasitic each on its own particular host.

840 species; the majority in the Tropics, especially Am. Many are ornamental plants. OFFICINAL: some on account of their purgative properties: the tuberous roots of _Ipomæa purga_ (Jalap, from Mexico) and the dried latex (“Scammony”) of _Convolvulus scammonia_ (from the East). The tuberous roots of _Batatas edulis_ (Trop. S. Am.) are used as a common vegetable (Sweet Potato) in the Tropics.

Family 30. =Personatæ.=

The type of the flower is: S5, P5, A5 (of which one, or in some cases several, are suppressed), and G2. The flowers are _hypogynous_, ☿, perfect with gamopetalous corolla, but most frequently irregular (medianly zygomorphic, except _Solanaceæ_), the _corolla_ being _bilabiate_ (divided into a posterior part of two lobes and an anterior part of three lobes), and the _stamens_ 4, _didynamous_ (the posterior being suppressed). The ovary has 2 loculi (only 1 in _Utriculariaceæ_, _Gesneriaceæ_, _Orobanche_); the placenta in the first-named orders (1–7) is most frequently very thick, and bears a _great many ovules_ (Figs. 554, 555, 557, 562); the number of ovules in the last orders (8–9) is considerably reduced (Fig. 570).

Special mention may be made of the apparently 4-merous flower which is found, _e.g._ in _Veronica_ and _Plantago_ (Figs. 567, 562 _C_, 570, 571), and which arises from the typical 5-merous flower by the suppression of the posterior sepal and the posterior stamen, and by the union of the two posterior petals into one.--Terminal flowers very seldom occur on the main axis, and would not harmonise well with the very irregular form of the flower. When they do occur, they are, as a rule, “peloric,” _i.e._ regular (in _Linaria vulgaris_ two kinds of peloric flowers occur,--one with 5 spurs, and one without spurs). The halves of the anthers are often divided as far as the base, and laterally so widely separated from each other as to assume an almost straight line (Figs. 563, 564). There is generally a nectary (“disc”) round the base of the ovary, often 5-lobed (or divided into free glands).--A common vegetative characteristic is the _absence of stipules_.

The 9 orders of the Personatæ are: 1, Solanaceæ; 2, Nolanaceæ; 3, Scrophulariaceæ; 4, Utriculariaceæ; 5, Gesneriaceæ; 6, Bignoniaceæ; 7, Pedaliaceæ; 8, Acanthaceæ; 9, Plantaginaceæ.

Order 1. =Solanaceæ.= The flower (Figs. 554, 555, 559) is hypogynous, regular (zygomorphic in _Hyoscyamus_), ☿, and gamopetalous, with S5, P5 (most frequently _imbricate_ or _valvate_), A5, G2, the 2 carpels being placed obliquely (Fig. 554); the bilocular ovary has a very _thick axile placenta_ (Figs. 554, 555 _H_, 557), which extends almost as far as the wall of the ovary. The fruit is a capsule or berry; the seeds are more or less reniform, and the embryo is _curved_ (rarely straight), in a fleshy endosperm (Figs. 555 _F_, _G_; 561).--Both arborescent and herbaceous forms are found in the order; leaves scattered without stipules, but with variously formed laminæ (always penninerved). _A peculiar leaf-arrangement_ is found in many species, viz. the leaves are borne _in pairs, a large and a smaller one together_; these pairs stand in 2 rows, and the flowers are then situated _between_ the individual leaves in each pair, apparently _not_ in a leaf axil. The inflorescences are frequently unipared scorpioid cymes without floral-leaves.

Zygomorphic flowers occur, and thus form a transition to the closely allied Scrophulariaceæ; the zygomorphy sometimes shows itself only in the relative length of the stamens, sometimes also in the corolla (_Hyoscyamus_).--_Nicandra_ is 5-merous throughout all the whorls.--The peculiar relative _leaf-arrangement_ in this order occurs from sympodial branching and displacement. The most simple is, _e.g._ _Datura_ (Fig. 556 _A_); each shoot-generation in the floral parts of the plant has only 2 foliage-leaves (_f^1_ and _f^2_), and then terminates in a flower; the axillary buds of both the foliage-leaves are developed and form a dichasium, but since the leaves are displaced on their axillary-shoots as far, or almost as far, as the first leaf of these axillary-shoots, the flowers are borne singly on the dichasial branches, and all the branches appear to be without subtending leaves (Shoot I is white, II shaded, III white, etc., diagram _A_). _Scopolia_ and others (Fig. 556 _B_) differ in that the lowest and smallest (_f^1_) of the two leaves on each shoot is barren, and is therefore not displaced; but the upper one (the second bracteole, _f^2_) is displaced as in the first instance, and consequently it assumes a position near the first leaf (the shaded leaf _f^2_ of shoot I being placed near the white leaf _f^1_ of shoot II, etc.,) of the next youngest shoot-generation, and hence the leaves are borne in pairs; the flower placed between the two leaves of a pair is therefore the terminal flower of the shoot to which the smaller of the two leaves belongs, and the larger leaf is the subtending leaf for the floral shoot itself.

=A.= FRUIT A CAPSULE. _Nicotiana_ (Tobacco) has a 2-valved capsule with septifragal dehiscence; the valves separate at the apex; the corolla is funnel-shaped, tubular, salver-shaped or campanulate. The flowers in panicles.--_Datura_ (_D. stramonium_, Thorn-apple) has a (frequently spiny) capsule (Fig. 558), which is _falsely 4-locular_ (at the top, bilocular) and opens septifragally with 4 valves. The lower part of the calyx persists as a thick collar (see Fig. 558). The corolla is funnel-shaped. The flowers are solitary, large.--_Hyoscyamus_ (_H. niger_, Henbane) has a pyxidium (Fig. 557) enclosed in the campanulate, completely persistent, thick-walled calyx. The flowers are slightly _zygomorphic_, and borne in unipared scorpioid cymes. ~_Scopolia_ (pyxidium); _Fabiana_ (Heather-like shrub); _Petunia_ (slightly zygomorphic flower; funnel-shaped corolla); _Nierembergia_; _Brunfelsia_ (almost a drupe); _Franciscea_; _Browallia_.~--Among those with capsular fruits are found the most anomalous forms, which by their zygomorphic flowers and often didynamous stamens present the transition to the Scrophulariaceæ: _Salpiglossis_; _Schizanthus_ (lobed petals; 2 perfect, and 3 rudimentary stamens).

=B.= FRUIT A BERRY. _Solanum_ (Nightshade); rotate corolla (Fig. 559). The stamens have short filaments, the anthers stand erect, close together round the style, like a cone in the centre of the flower, and open by pores at the apex (Fig. 560). ~_S. tuberosum_ (the Potato-plant); the Potato-tuber is a swollen, underground stem; the “eyes” are buds, situated in the axils of its scale-like, quickly-perishing leaves.~--_Lycopersicum_ resembles _Solanum_ in the flower, but the united anthers open by longitudinal clefts and have an apical appendage. The cultivated species, _L. esculentum_ (Tomato), has often a higher number than 5 in the flower, and in the fruit several loculi of unequal size.--_Physalis_ (Winter Cherry); the calyx ultimately swells out in the form of a bladder, becomes coloured, and loosely envelopes the spherical berry.--_Capsicum_ (Guinea Pepper-plant); some species have very large, irregular, rather dry (red, yellow, black) berries, which are unilocular in the upper part.--_Lycium_ (false Tea-plant); the corolla is salver- or funnel-shaped; shrubs; often thorny.--_Atropa_ (_A. belladonna_, Deadly Nightshade, Fig. 555); corolla campanulate; the calyx projects beneath the spherical, black berry. The flowers are borne singly.--_Mandragora_; (Mandrake); _Nicandra_ (ovary often 5-locular).--~A small tropical group: CESTREÆ (_Cestrum_, _Habrothamnus_, etc.) has an almost _straight_ embryo, which may also be found _e.g_. in species of _Nicotiana_. Related to the Scrophulariaceæ.~

About 1,500 species; the majority within the Tropics, outside these limits especially in America. _Solanum nigrum_ is a common weed.--_The Potato-plant_ (_Solanum tuberosum_), from Peru and Chili, was introduced into Europe in 1584 by Sir Walter Raleigh. (Potatoes = Batatos). The fruits of several serve as _condiments_: Chilies or Pod-pepper (_Capsicum annuum_ and _longum_), and the Cayenne-pepper (_C. baccatum_ and others), whose fruits also are officinal, were brought to Europe from S. America by Columbus, and are commonly cultivated in Tropical America; _Lycopersicum esculentum_ (Tomato) and others from Peru; _Solanum ovigerum_ (Egg-plant); _Solanum melongena_, etc. _Poisonous_, _acrid_, _narcotic_ properties (alkaloids, etc., solanine, nicotine, atropine, hyoscyamine) are found in many: _Atropa belladonna_ (from S. Europe; the roots and leaves are officinal); _Solanum dulcamara_ (Bitter-sweet; formerly officinal), _S. toxicarium_ (Guiana); _Datura stramonium_ from Asia (leaves and seeds officinal), _D. sanguinea_, _metel_, _tatula_, and others; _Hyoscyamus_ (officinal: the leaves and seeds of _H. niger_); _Nicotiana tabacum_ (Virginian tobacco, officinal: the leaves), _N. rustica_ and others from Trop. America (_Tobacco_ was introduced into Europe in 1560); _Cestrum_-species. _Duboisia myoporoides_ (Australia); the leaves contain _hyoscyamine_ and are used in medicine. A number of species of these genera are ornamental plants.

Order 2. =Nolanaceæ.= These most resemble the Convolvulaceæ in the corolla, but the Solanaceæ in their branching, and leaf-arrangement (in pairs, etc.). The diagram is the same as in _Nicandra_ with 5 carpels, but the fruits of this order most frequently form, by invaginations in various directions, an ovary (with 1 style) consisting of numerous and irregularly grouped, 1-ovuled cells; the fruit is a schizocarp with many 1-seeded fruitlets.--_Nolana_ (Western S. America): a few are ornamental plants.

Order 3. =Scrophulariaceæ.= The flower is hypogynous, ☿, _zygomorphic_, with the usual type: S5, P5, A5, and G2, the latter placed _in the median plane_; some genera have all 5 stamens developed (Fig. 562 _A_), but most frequently the posterior one is suppressed and the flower becomes _didynamous_ (Fig. 562 _B_). The fruit, as in the capsular-fruited Solanaceæ, is a bilocular, 2-valved _capsule_, with a _thick, axile placenta_, and most often septicidal dehiscence (Fig. 563 _C_). The _numerous seeds_ are not reniform as in many Solanaceæ, and have a _straight, or only slightly curved embryo_, with abundant endosperm (Fig. 563 _D_).--The majority are herbs; some are arborescent; the leaves are opposite or scattered, but stipules are wanting as in the whole family.

The Scrophulariaceæ are closely allied to the Solanaceæ, and there is, properly speaking, no characteristic feature which absolutely separates them. The somewhat irregular corolla, with five stamens of unequal length in _Verbascum_, is also found in _Hyoscyamus_; curved and straight embryos are found in both orders. The activation of the corolla in the Scrophulariaceæ is _simple imbricate_, in the Solanaceæ most frequently _folded imbricate_ (in _Atropa_ and those allied to it, imbricate without folding). The genera (about 164) are distinguished according to the form of the corolla, number of stamens, inflorescence, arrangement of the leaves, etc. _Verbascum_ belongs to the most primitive 5-stamened forms, and from it proceed a long series down to _Veronica_, with only two stamens and most frequently the posterior sepal suppressed.

=1.= ANTIRRHINEÆ, SNAPDRAGON GROUP. This has most frequently a descending æstivation of the petals (the posterior petals are outside the lateral ones, which again enclose the anterior; Fig. 562 _A_, _B_). The plants belonging to this group are not parasites.