Part 36

Order 11. =Lauraceæ= (=True Laurels=). Trees or shrubs; the leaves, always without stipules, are simple, most frequently scattered, lanceolate or elliptical, entire, penninerved, finely reticulate (except _Cinnamomum_ with 3–5-veined leaf), leathery and evergreen (except, _e.g. Cinnamomum_); they are frequently studded with clear glands containing _volatile oil_. The flowers are borne in panicles and are small and of a greenish or whitish colour. They are _regular, perigynous_, with most frequently a bowl or cup-shaped receptacle (Fig. 386), usually ☿, and _trimerous_ (rarely dimerous) through all (most frequently 6–7) whorls; viz. most frequently, perianth 2 whorls, stamens 3–4 and carpels 1 (P3 + 3, A3 + 3 + 3 + 3, G3) in regular alternation (Fig. 387). Each of the 2 or 4 loculi of the anthers _open by an upwardly directed valve_ (Fig. 386); of the stamens, the 2 outermost whorls are generally introrse, the others extrorse, or 1–3 whorls are developed as staminodes (Fig. 387 _g_). The gynœceum has 1 loculus with 1 style and 1 pendulous ovule (Fig. 386), and may be considered as formed of 3 carpels. The fruit is a _berry_ (Fig. 388) or _drupe_, which often is surrounded at its base by the persistent receptacle (as an acorn by its cupule), which becomes fleshy and sometimes coloured during the ripening of the fruit. The embryo has 2 thick cotyledons, but _no endosperm_ (Fig. 388).

The Lauraceæ present affinities with the Polygonaceæ, in which there is found perigyny, as well as a similar number of parts in the flower and a similar gynœceum, but with erect and orthotropous ovule. From their general characters they should be classed among the Polycarpicæ, but stand, however, isolated by the _syncarpous_ gynœceum, if it is in reality formed by 3 carpels and not by 1 only. _Hernandia_, which has epigynous monœcious flowers, deviates most.--_Cassytha_ is a _Cuscuta_-like, herbaceous, slightly green parasite with twining, almost leafless stems. The flower however agrees with the diagram in Fig. 387. Some Lauraceæ have curved veins or palminerved and lobed leaves (often together with entire ones) _e.g. Sassafras_.

There are 1000 species; especially in the forests of tropical S. America and Asia, of which they form the principal part. Only _Laurus nobilis_ is found in Europe, and there is little doubt that its proper home is in Western Asia. They are rare in Africa.--On account of _the volatile oil_ found in all parts of the plant, they are used as _spices_, _e.g._ the false Cinnamon-tree (_Dicypellium caryophyllatum_, in the Brazils). The OFFICINAL ones are--the Cinnamon-tree (_Cinnamomum zeylanicum_ from Ceylon, E. India, Eastern Asia), which is also cultivated; the Camphor-tree (_Cinnamomum camphora_, Eastern Asia). The Laurel-tree (_Laurus nobilis_, Mediterranean), the berries and leaves of which give laurel oil, is medicinal.--Scented wood for furniture, etc., is obtained from _Sassafras officinalis_ (from N. Am.). The wood from its roots is officinal. Pichurim “beans” are the large cotyledons of _Nectandra pichury_, whilst the famous “Greenheart” wood of Demarara is the wood of _Nectandra rodiæi_. The pulp and seeds contain a _fatty oil_. The pear-like fruit of _Persea gratissima_ (Mexico, also cultivated) is very delicious. _Lindera benzoin_ is a garden shrub; _Laurus nobilis_ likewise.

Order 12. =Myristicaceæ= (=Nutmegs=). In this order there is only 1 genus, _Myristica_. Trees or shrubs. The leaves agree closely with those of the Lauraceæ, with which this order has many points in common. The majority of the species are aromatic, having in their vegetative parts pellucid glands with volatile oils. The flowers are regular, diœcious, trimerous, and have a single gamophyllous (cupular or campanulate) 3-toothed, fleshy perianth. In the ♂-flowers the anthers vary in number (3–15), and they are extrorse and borne on a centrally-placed column; in the ♀-flower the gynœceum is unilocular, unicarpellary, with 1 ovule. The FRUIT (Fig. 389) has the form of a pear; it is a fleshy, yellow capsule, which opens along the ventral and dorsal sutures, exposing the large seed. This seed has a large, red, irregularly branched aril--the so-called “mace”; the “nutmeg,” on the other hand, is the seed itself with the inner thin portion of the testa, which has pushed its way irregularly into the endosperm, and causes the marbled appearance of the cut seed (Fig. 390); the external, dark brown, hard, and brittle part of the seed-shell is however removed. Mace and nutmeg contain volatile and fatty oils in abundance.--80 species. Tropical. The majority are used on account of their aromatic seeds and aril, the most important being _M. fragrans_ (_moschata_), from the Moluccas. This is cultivated in special plantations, not only in its native home, but in other tropical countries also. Nutmegs were known as commodities in Europe in very ancient times (_e.g._ by the Romans), but it was not until the year 1500 that the tree itself was known. The seed is OFFICINAL.

Family 10. =Rhœadinæ.=

The plants belonging to this family are almost exclusively herbaceous, with scattered, exstipulate leaves. The flowers are eucyclic di- or tetramerous, with the calyx and corolla deciduous, _hypogynous_, ☿, _regular_, the gynœceum with 2–several carpels (generally 2, transversely placed) (Figs. 391, 392, 393, 397). The ovary is _unilocular with parietal placentæ_, but in _Cruciferæ_ and a few others it becomes bilocular by the development of a _false_, membranous wall between the placentæ. The stigmas in the majority of cases are _commissural_, _i.e._ they stand above the placentæ, and not above the dorsal line of the carpels. The fruit is nearly always a _capsule_, which opens by the middle portions of the carpels detaching themselves as valves, bearing no seed, whilst the placentæ persist as the seed-bearing frame. Endosperm is found in _Papaveraceæ_ and _Fumariaceæ_, but is absent in _Cruciferæ_ and _Capparidaceæ_.--~This family through the Papaveraceæ is related to the Polycarpicæ (the Nymphæaceæ), through the Capparidaceæ to the Resedaceæ in the next family.~

Exceptions to the above are: _Eschscholtzia_, _Subularia_ (Fig. 403) and a few Capparidaceæ, in which perigynous flowers are found. A few Papaveraceæ and Fumariaceæ have trimerous flowers. In _Fumaria_ and certain Cruciferæ, the fruit is a nut. The Fumariaceæ have zygomorphic flowers. Trees and shrubs are almost entirely confined to the Capparidaceæ, in which order stipules also are found.

Order 1. =Papaveraceæ= (=Poppies=). Herbaceous plants with stiff hairs and _latex_; flowers _regular_ (Fig. 391) with generally 2 (-3) sepals (which _fall off_ as the flower opens), 2 + 2 petals (imbricate and crumpled in the bud) _without spur, numerous stamens in several alternating whorls_ (generally a multiple of 2); carpels 2–several, united into a unilocular gynœceum. Trimerous flowers also occur. Capsule with very numerous seeds on the parietal placentæ; embryo small, with large, oleaginous _endosperm_ (Fig. 392).--The leaves have no stipules and are generally pinnately lobed.

_Papaver_ (Poppy) has large, solitary, terminal flowers; petals firmly and irregularly folded in æstivation; gynœceum formed by many (4–15) carpels; stigmas velvety, _sessile_ and _stellate_ (the rays stand above the placentæ) (Fig. 391 _B_). The edges of the carpels project deeply into the ovary, but do not meet in the centre, so that it remains unilocular. The capsule opens by pores placed close beneath the stigma, and formed of small valves alternating with the placentæ and the rays of the stigma (Fig. 391). _P. dubium_, _P. argemone_, _P. rhœas_.--_Chelidonium_ (Greater Celandine) has _yellow_ latex, flowers in umbellate cymes (the terminal, central flower opening first) and only 2 carpels; the fruit resembles the siliqua of the Cruciferæ in having two _barren valves_, which are detached from the base upwards, and a _seed-bearing frame_, but there is no partition wall formed between the placentæ. _Ch. majus._--~The majority of the other genera have, like _Chelidonium_, 2 carpels (lateral and alternating with the sepals: Fig. 391 _A_) and siliqua-like fruit, thus: _Eschscholtzia_ (perigynous) with a linear, stigma-bearing prolongation extending as far above the placentæ as above the dorsal suture of the carpels; _Glaucium_ (Horn-Poppy); _G. luteum_, whose extremely long, thin capsule differs from that of _Chelidonium_ by the formation, during ripening, of a thick, spongy (_false_) replum, which persists when the valves are detached; _Sanguinaria_ with red latex, the 2 petals divided into 8–12 small petals (perhaps by dédoublement); _Macleya_ and _Bocconia_ (1-seeded capsule) with 2 sepals and no petals.--Trimerous flowers are found in _Argemone_ and _Platystemon_ (with a curious fruit, carpels free, and transversely divided and constricted into joints which separate as nut-like portions).--_Meconopsis._--_Hypecoum_ (Fig. 393 _C_) has tri-lobed and three cleft petals, 4 free stamens with 4-locular anthers and a jointed siliqua; it presents a transitional form to the Fumariaceæ, with which order it is sometimes included.~

POLLINATION. _Papaver_ and _Chelidonium_ have no honey, and are without doubt only visited by insects for the sake of the pollen. The anthers and stigmas mature about the same time.--There are 80 species; especially from warm climates. OFFICINAL: _Papaver somniferum_ (Opium-Poppy); the latex of its unripe capsules is obtained by incisions, and dried (_opium_); it contains many alkaloids: morphine, papaverine, narcotine, thebaine, etc. The oleaginous seeds are also used in the manufacture of oil. Its home is in the East, where it is extensively cultivated. The petals of the Corn-poppy (_P. rhœas_) are also officinal. Several species are cultivated as ornamental plants.

Order 2. =Fumariacæ= (=Fumitories=). This order differs from the closely allied Papaveraceæ in the absence of latex, a poorer flower, generally _transversely zygomorphic_ (Fig. 393 _B_), in which case one or both of the outer lateral petals are gibbous, or prolonged into a spur; the stamens are especially anomalous. Sepals =2=, caducous; petals 2 + 2; stamens 2, _tripartite_; each lateral anther is _bilocular_ (Figs. 393 _A_, _B_; 395); gynœceum bicarpellate. The fruit is a nut or siliqua-like capsule. _Endosperm._--_Herbs_ with scattered, repeatedly pinnately-divided leaves without stipules, generally quite glabrous and glaucous; the flowers are arranged in racemes with subtending bracts, but the bracteoles are sometimes suppressed.

_Dicentra_ (syn. _Dielytra_) and _Adlumia_ have a doubly symmetrical flower, with a spur or gibbous swelling at the base of _each_ of the laterally-placed petals (Figs. 393 _A_, 394). _Corydalis_ has a zygomorphic flower, _only one of_ the lateral petals _having a spur_, and consequently there is only one nectary at the base of the bundle of stamens, which stands right in front of the spur (Fig. 393 _B_, 395, 396). The fruit is a many-seeded siliqua-like capsule. ~A peculiarity of the flower is that the plane of symmetry passes _transversely_ through the flowers, whilst in nearly all other zygomorphic flowers it lies in the median line. Moreover, the flower is turned, so that the plane of symmetry ultimately becomes nearly vertical, and the spur is directed backwards.--Many species have subterranean tubers; in these the embryo germinates with _one cotyledon_, which is lanceolate and resembles a foliage-leaf. The tuber is in some the swollen hypocotyl (_C. cava_), in others a swollen root (_C. fabacea_, etc.), which grows down through the precisely similar swollen root of the mother-plant. The sub-genus _Ceratocapnos_ has dimorphic fruits (nuts and capsules) in the same raceme.~ _Fumaria_ differs from _Corydalis_ only by its almost drupaceous, one-seeded nut (Fig. 395).

THE STRUCTURE OF THE FLOWER. _Hypecoum_ among the Papaveraceæ is the connecting link with the Fumariaceæ. The diagram (Fig. 393 _C_) corresponds both in number and in the relative position of its members with that of most of the other Papaveraceæ (Fig. 391), except that there are only four stamens (with extrorse anthers). In _Dicentra_ (Fig. 393 _A_), the two central (uppermost) stamens are absent, but each of the two lateral ones are divided into three filaments, of which the central one bears a four-locular anther, and each of the others a two-locular (half) anther. _Corydalis_ and _Fumaria_ stand alone in the symmetry of the flower, differing from _Dicentra_ in having only one of the lateral petals (Fig. 393 _B_, _sp_) prolonged into a spur, while in _Dicentra_ both the petals are spurred. This structure has been interpreted in various ways. According to Asa Gray the median stamens are absent in the last-named genera, and the lateral ones are split in a similar manner to the petals of _Hypecoum_. Another, and no doubt the most reasonable theory (adduced by De Candolle), is: that two median stamens are split, the two parts move laterally, each to their respective sides and become united with the two lateral stamens; this affords a natural explanation of the two half-anthers, and establishes a close relationship to the Cruciferæ. A third interpretation, held by Eichler and others, is as follows: the median stamens are _always_ wanting; when they appear to be present, as in _Hypecoum_, it is due to the fact that the side portions of the lateral stamens _approach each other_ (as interpetiolar stipules) and coalesce into an apparently single stamen.

130 species; mostly from the northern temperatures.

POLLINATION. _Fumaria_, with its inconspicuous flowers, has to a great extent to resort to self-pollination. _Corydalis_, on the other hand, is dependent on cross-pollination; _C. cava_ is even absolutely sterile with its own pollen. _Corydalis_ is pollinated by insects with long probosces (humble-bees, bees), which are able to reach the honey secreted in the spur; as they alight on the flowers they press the exterior petals on one side (Fig. 396 _e_), so that the stigma, surrounded by the anthers, projects forward; the proboscis is introduced in the direction of the arrow in the figure, and during this act the under-surface of the insect is covered with pollen, which is transferred by similar movements to the stigma of another (older) flower.--Ornamental plants; _Dicentra_ (_spectabilis_ and _eximia_), _Adlumia_, _Corydalis_.

Order 3. =Cruciferæ (Crucifers).= The flowers are _regular_, ☿; sepals 4, free (2 + 2), deciduous; petals 4, free, deciduous, unguiculate, placed _diagonally_ in one whorl, and alternating with the sepals; stamens 6; the 2 _outer_ are _short_, the 4 _inner_ (in reality the two median split to the base) _longer_, placed in pairs (tetradynamia of Linnæus); gynœceum syncarpous formed by 2 (as in the previous order, lateral) carpels, with 2 parietal placentæ, but divided into two loculi by a _spurious_ membranous dissepiment (_replum_) (Fig. 397). Style single, with a capitate, usually two-lobed stigma, generally commisural, that is, placed above the parietal placentæ (Fig. 397), but it may also be placed above the dorsal suture, or remain undivided. Ovules _curved_. The fruit is generally a bivalvular _siliqua_ (Fig. 398 _B_, _C_), the valves separating from below upwards, and leaving the placentæ attached to the replum; other forms of fruits are described below. The oily seeds _have no endosperm_ (endosperm is present in the two previous orders); the _embryo is curved_ (Figs. 398 _E_, _F_; 399, 400).--In general they are _herbaceous_ plants, without latex, with scattered, penninerved leaves, without stipules; the inflorescence is very characteristic, namely, a raceme with the flowers aggregated together at the time of flowering into a corymb, and _destitute of both bracts and bracteoles_.

Many are biennial, forming in the first year a close leaf-rosette. By cultivation the tap-root can readily be induced to swell out into the form of a tuber (Turnips, Swedes, etc.). _Stipules_ are found indicated by small glands on the very young leaves; in _Cochlearia armoracia_ they are fairly large triangular scales. _Stellate hairs_ often occur. _Floral-leaves_ are occasionally developed. Terminal flowers are never found in the inflorescences. _Iberis_ and _Teesdalia_ have _zygomorphic_ flowers. _Subularia_ (Fig. 403) is perigynous. The 2 external sepals (Fig. 397) stand in the median plane; it may therefore be supposed that there are two bracteoles outside these which, however, are suppressed, and can only in a few instances be traced in the young flower; the two lateral sepals are often gibbous at the base, and serve as reservoirs for the nectar secreted by the glands placed above them; they correspond in position to the external petals of the Fumariaceæ. The 4 petals which follow next arise simultaneously, and alternate with the 4 sepals; if it could be shown that these are merely 2 median petals, which have been deeply cleft and the two parts separated from each other and displaced to the diagonal position, there would be a perfect correspondence with the Fumariaceous flower; then the petals would be followed in regular alternation by the 2 lateral small stamens, the 2 median long stamens, which it has been proved are split into 4 and placed in couples, and the 2 laterally-placed carpels,--in all 6 dimerous whorls. But the formation of the corolla by the splitting of 2 petals does not agree with the development of the flower or bear comparison, and hence the only fact in favour of this theory is the otherwise prevailing correspondence with the Fumariaceæ. Yet it may be observed that in special cases each pair of long stamens clearly enough arises from one protuberance and even later on may be considerably united or entirely undivided (_e.g._ _Vella_); in other instances they are quite distinct from the beginning, and it is possible that this latter condition has become constant in the corolla. _Lepidium ruderale_ and others have no corolla. _Senebiera didyma_ has only 2 median stamens. _Megacarpæa_ has several stamens, no doubt by dédoublement, as in Capparidaceæ.--The _number of carpels_ may also be abnormally increased; _Tetrapoma barbareifolium_ has normally 4 carpels with an equal number of placentæ and repla. It is supposed to be a variety of _Nasturtium palustre_.--The 2–4–8–10 greenish _glands_, which are found at the base of the stamens, are nectaries, morphologically emergences, and not rudimentary stamens. The forms of _fruits_ are of great systematic significance, see the genera. In some species dimorphic fruits are present, _e.g. Cardamine chenopodiifolia_ which has both ordinary _Cardamine_-siliquas and 1-seeded siliculas.

The _curved embryo_ appears in five forms, which have systematic importance: 1. To the PLEURORHIZÆ belong those genera whose radicle (with the hypocotyl) lies bent upwards along the _edge_ of the _flat_ cotyledons (Fig. 399); to this group belong _Cardamine_, _Nasturtium_, _Cheiranthus_, _Matthiola_, _Cochlearia_, _Draba_, _Iberis_, _Thlaspi_, etc.; diagrammatic transverse section: ◯=.--2. To NOTORHIZÆ belong those whose radicle lies in an upward direction along the _back_ of one of the _flat_ cotyledons (Figs. 400, 413); _e.g._ _Hesperis_, _Sisymbrium_, _Lepidium_, _Capsella_, _Camelina_: ◯‖.--3. ORTHOPLOCEÆ differ from the Notorhizeæ in having the cotyledons folded (not flat) (Fig. 398 _E_, _F_); to this belong _Brassica_, _Sinapis_, _Raphanus_, _Crambe_, etc.: ◯>>.--4. SPIROLOBEÆ: the radicle lies as in the Notorhizæ, but the cotyledons are so rolled together that a transverse section of the seed cuts them twice; _Bunias_: ◯‖‖.--5. DIPLECOLOBEÆ: the cotyledons are folded forward and backward so that a transverse section cuts them several times; _Subularia_, _Senebiera_: ◯‖‖‖.

On _germination_ the cotyledons appear above the ground as green leaves; in the Orthoploceæ they are bilobed, in the _Lepidium_-species divided.

1. =Silicula, broad replum= (Siliculosæ latiseptæ), valves flat or slightly vaulted, and the replum extends through the greatest width of the silicula (Fig. 404). The seeds are situated in two rows.

◯=: _Cochlearia_ (Horse-radish): the siliqua is nearly spheroid; glabrous herbs, generally with fleshy, stalked leaves, and white flowers.--_Draba_ has an oblong, lanceolate, somewhat compressed silicula; herbs with small rosettes of leaves, most frequently with stellate and long-stalked racemes.--_Alyssum_ and _Berteroa_ are whitish, on account of the stellate hairs; they have a more compressed and round or elliptical silicula. _Vesicaria_; _Aubrietia_. _Lunaria_ (Honesty, Fig. 401): very broad and flat silicula with long stalk (the receptacle as in Capparidaceæ).

◯‖: _Camelina_ (Gold-of-pleasure) has a spheroid, pear-shaped siliqua with a small rim passing right round (Fig. 402). _Subularia_ (Awlwort), an aquatic plant with _perigynous_ flower (Fig. 403) and folded cotyledons.

2. =Silicula, narrow replum= (Siliculosæ angustiseptæ), _i.e._ the replum is much shorter than the arched, more or less boat-shaped valves (Figs. 405, 406, 407).