4. SOLANALES: SOLANACEAE
A. Leupen
Introduction
The plant family of the Solanaceae is one of the most intriguing plant families in the world. Not only because it is one of the largest families in plant kingdom with more than 3,000 species, but because it also includes species which are essential for life. There are important edible species such as the potato (Solanum tuberosum L.), eggplant (Solanum melongena L.) tomato (Solanum lycopersicum (L.) Karsten ex Farwell, chilli pepper, capsicum (Capsicum species) and cape gooseberry (Physalis peruviana L.). The plant family also includes species that are grown as ornamentals such as those belonging to the genera Browallia, Brunfelsia, Cestrum, Datura, Nicotiana, Salpiglossis, Solanum, Solandra, etc. Well known are the trumpet-like flowers of Datura species which are popular as ornamental plants and which can produce flowers of up to 30 cm. in a variety of colours. Plants of this family do good service as a medicine or narcotic e.g. Atropa belladonna L. with atropine as an active ingredient used in ophthalmology, as a dilatator of the pupil of the eye, thorn-apple leaves (Datura species) used in cigarettes as bronchi-dilatator for asthmatic patients and (luxury) tobacco (Nicotiana species). The plant family conjures up a lot of images in mythology, extracts have been used to stimulate hallucinations. The name Solanaceae is possibly derived from Solari which means ‘soothing’ in Latin. It might also be possible that the name night ‘shades’ refers to the toxicological properties of several Solanum species which can bring damage (Dutch: schade) to an individual, or refer to demoniacal powers (Danish: natskade or night-raven and Swedish: nattskata or bat). The link between the mid-Dutch word ‘nachtschaduw’ and the English word nightshade has herewith been established.
Classification
Place within the plant kingdom
Within the plant kingdom the plant family of the Solanaceae is situated as follows:
Division:Spermatophytae (seed-plants)
Sub-division: Angiospermae (having enclosed seeds)
Class:Dicotyledoneae (bi-cotyledons);Sympetalae (having united petals)
Order:Personatae (wearing a mask, having a prominent palate on the corolla)
Family:Solanaceae In addition the family is divided in sub-family, tribe (sub-tribes), genus (g., gen.), section (sect.), series (ser.), specie (sp.) and variant, form (f, forma), sub-species (ssp.).
The seed-plants (Spermatophytae) also called Anthophyta, have as a general characteristic: seed-bearing flowering plants. The seeds are contained in an ovarium, so the pollen-grains cannot come to the ovules directly, but fertilization takes place via the style (Angiospermae). The development of the embryo is by the two cotyledons (Dicotyledoneae). There is a long-living root and the transport-vessels are arranged into a circle. The leaves do have distinct petioles, are net-veined (reticulatovenosus) and often have small supporting leaflets. Pollination is simultaneous. The perianth is lobbed but grown together to some extend in calyx and corolla (sepals and petals respectively). There is only one ring of stamens alternating the petals (tetracyclideae). The flowers are tetracyclic which means radiar (*) or dorsi-ventralis (Å´). K(n) [C (n) An] G (n). In which: * radiar symmetric K calyx and n=5 C corolla and n=5 A Androecium (total number of male sex-organs:stamens and n=5) G Gynoecium (total number of female sex-organs: ovarium) - Hypogynium
Botany
Flowers mostly dorsi-ventralis with connate filaments. The flower is regularly symmetrical, gamopetalous, five numbered (seldom 3-10 sepals and seldom 10 petals). The flower is mostly androgynous and the disc is heightened. The flower is quinary and the ovary biloculair (Personatae). The corolla is round and flat, campanulate- or tubiformis (Sympataleae is bell-shaped or tube-shaped). The petals are grown together in a greater or lesser degree. The calyx is partly gamopetalous and mostly persistent after flowering. The transport vessels are bicollatoralis. The leaves are placed alternately, solitary and sometimes has deep incisions. In the vicinity of the flower the leaves are more opposite but not completely so. The gynoecium is hypogynus and is formed out of the two carpels (syncarp) which are situated obliquely with respect to the median. The placenta is gross. The gynoecium is mostly biloculair (real septum) or, as in the case of thornapple, apparently with four chambers due to the presence of four false septa (sometimes 3-5 chambers). The origin of the seed is with an integument. The perianth is quinary. The fruit is a dry capsule or a berry. There is only one style and the stigma is two-lobbed. The stamens are quinary (seldom 4-8), alternating with the lobes and adhering to the petals. The anthers usually touch each other but are not grown together. Mostly, the filaments are equal in size. The plants are herbs or shrubs, small trees or climbers. There are prickles in a lot of the species or at least they are covered with hairs. Some examples of representatives within this Family are given below.
Anatomy in detail
Habit and leaf form. Herbs, shrubs, trees, and lianas (often prickly); non-laticiferous and without coloured juice; resinous, or not resinous. ‘Normal’ plants (usually), or ‘normal’ plants to switch-plants (occasionally). Autotrophic. Annual, or biennial, or perennial; with a basal aggregation of leaves, or with neither basal nor terminal aggregations of leaves, or with terminal aggregations of leaves (e.g. in Anthocercis). Self supporting, or climbing; the climbers stem twiners, or scrambling. Helophytic to xerophytic. Leaves alternate, or alternate to opposite (usually alternate below, but often becoming opposite towards the inflorescence); usually spiral (at least below); ‘herbaceous’, or leathery, or modified into spines; petiolate (mostly), or subsessile, or sessile; non-sheathing; gland-dotted (rarely, e.g. Anthocercis), or not gland-dotted; aromatic, or foetid (assignment of (e.g.) Anthocercis as pleasant/unpleasant being a matter of opinion), or without marked odour (mostly); simple, or compound; epulvinate; when compound, ternate, or pinnate. Lamina dissected, or entire; when simple/dissected, pinnatifid, or spinose; pinnately veined; cross-venulate. Leaves exstipulate; without a persistent basal meristem. Domatia recorded (from 4 genera); represented by hair tufts.
General anatomy. Plants with ‘crystal sand’ (commonly), or without ‘crystal sand’.
Leaf anatomy. Stomata mainly confined to one surface, or on both surfaces; anomocytic, or anisocytic, or diacytic. Hairs usually present; multicellular. Multicellular hairs branched.
Lamina dorsiventral (usually), or isobilateral; without secretory cavities. The mesophyll containing mucilage cells (rarely), or not containing mucilage cells. Minor leaf veins without phloem transfer cells (5 genera).
Stem anatomy. Cork cambium present; initially deep-seated, or superficial. Nodes unilacunar (with 2 or 3 traces). Primary vascular tissue bicollateral. Internal phloem present. Secondary thickening developing from a conventional cambial ring (usually), or anomalous; from a single cambial ring. ‘Included’ phloem present (occasionally, e.g. Atropa belladonna rhizomes), or absent. Xylem with tracheids, or without tracheids; with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; with vessels. Vessel end-walls simple. Wood parenchyma apotracheal, or paratracheal. Sieve-tube plastids S-type.
Reproductive type, pollination. Plants hermaphrodite (mostly), or monoecious, or andromonoecious, or dioecious (e.g. sometimes in Solanum and Symonanthus). Entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’. The terminal inflorescence unit apparently cymose. Inflorescences terminal, or axillary, or leaf-opposed (occasionally). Flowers small to medium-sized; fragrant (e.g. Nicotiana), or malodorous (e.g. Anthocercis, if so considered), or odourless (mostly); regular (usually, more or less), or somewhat irregular to very irregular. The floral irregularity when noticeable) involving the perianth, or involving the androecium, or involving the perianth and involving the androecium. Flowers mostly (4–)5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk usually present; intrastaminal.
Perianth with distinct calyx and corolla; 10 (nearly always), or 8, or 11–14; 2 whorled; isomerous, or anisomerous. Calyx (4–)5(–7); 1 whorled; gamosepalous. Calyx lobes markedly shorter than the tube to markedly longer than the tube. Calyx regular (usually), or unequal but not bilabiate; persistent; accrescent, or non-accrescent. Corolla (4–)5(–7); 1 whorled; gamopetalous. Corolla lobes markedly shorter than the tube to markedly longer than the tube. Corolla contorted and plicate (usually), or imbricate, or valvate, or contorted; rotate, or campanulate, or funnel-shaped, or tubular; regular (usually, more or less), or bilabiate (rarely), or unequal but not bilabiate (sometimes).
Androecium 5 (usually), or 3–4 (rarely), or 6–7 (rarely). Androecial members adnate (epipetalous, on the tube); all equal (often), or markedly unequal; free of one another; 1 whorled. Androecium exclusively of fertile stamens (usually), or including staminodes (Salpiglossideae). Staminodes when present, 1 (Salpiglossis), or 3 (Schizanthus); in the same series as the fertile stamens; representing when present, the posterior median member (Salpiglossis), or the posterior median member and the posterior-lateral pair (Schizanthus). Fertile stamens representing the posterior median member, the posterior-lateral pair, and the anterior-lateral pair (mostly), or the posterior-lateral pair and the anterior-lateral pair (Salpiglossis), or the anterior-lateral pair(Schizanthus). Stamens 5 (in all but Salpiglossideae), or 2, or 4; inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; didynamous (e.g. Anthocercis), or not didynamous, not tetradynamous (mostly); reduced in number relative to the adjacent perianth (rarely), or isomerous with the perianth; oppositisepalous; alternating with the corolla members. Filaments appendiculate (e.g., inconsistently lobed in Anthocercis), or not appendiculate. Anthers connivent (often touching in a ring at their tops), or separate from one another; dorsifixed, or basifixed; dehiscing via pores to dehiscing via short slits (terminally), or dehiscing via longitudinal slits; extrorse (e.g. Anthocercis), or introrse (usually, if dehiscence not terminal); tetrasporangiate. Endothecium developing fibrous thickenings, or not developing fibrous thickenings (when the dehiscence is porose). Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral, or decussate. Anther wall initially with one middle layer, or initially with more than one middle layer (1 or 2); of the ‘basic’ type (rarely), or of the ‘dicot’ type. Tapetum glandular. Pollen shed in aggregates (rarely), or shed as single grains; in Salpiglossis, in tetrads. Pollen grains aperturate (usually), or nonaperturate; (2–)3–5(–6) aperturate; colpate, or colporate (or colporoidate), or rugate; 2-celled.
Gynoecium 2 carpelled. Carpels reduced in number relative to the perianth. The pistil 2 celled (usually), or 3–5 celled (Nicandreae and Datureae). Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 2 locular (but sometimes complicated by secondary divisions). Locules secondarily divided by ‘false septa’ (Nicandreae and Datureae), or without ‘false septa’. Gynoecium oblique (the posterior carpel to the right, as expressed in conventional floral diagams); stylate. Styles 1; without an indusium; attenuate from the ovary; apical. Stigmas 1–2; if regarded as single, 2 lobed; wet type, or dry type; papillate, or non-papillate; Group II type, or Group III type, or Group IV type. Placentation axile (the placentae usually more or less swollen). Ovules 1–50 per locule (i.e. to ‘many’); non-arillate; anatropous, or hemianatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type, or Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral (usually), or persistent (e.g. Atropa). Synergids pear-shaped, or hooked (sometimes with filiform apparatus). Endosperm formation cellular, or nuclear, or helobial. Endosperm haustoria usually present; antipodal. Embryogeny solanad (usually), or onagrad (rarely).
Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a capsule, or a berry, or a drupe. Capsules septicidal (commonly), or loculicidal, or valvular, or circumscissile (Hyoscyamus). Seeds endospermic (usually). Endosperm oily (usually), or not oily (rarely starchy). Seeds not conspicuously hairy. Seeds with starch (rarely), or without starch. Cotyledons 2; semi-cylindric. Embryo achlorophyllous (13/21); straight, or straight to curved, or curved (curved through more than a semicircle to annular in Nicandreae, Solaneae and Datureae, but straight to only slightly curved in Cestreae and Salpiglossideae).
Seedling. Germination phanerocotylar.
Physiology
Cyanogenic, or not cyanogenic. Alkaloids present (mostly), or absent. Iridoids not detected. Arthroquinones detected (Fabiana); polyacetate derived. Proanthocyanidins absent. Flavonols present, or absent; kaempferol and quercetin (mostly). Ellagic acid absent (25 species, 14 genera). Arbutin absent. Ursolic acid present. Saponins/sapogenins present, or absent. Aluminium accumulation demonstrated (rarely). Sugars transported as sucrose (in Datura, Solanum). Inulin recorded (Solanum, Gibbs 1974). C3. C3 physiology recorded directly in Datura, Lycium, Lycopersicon, Nicotiana, Petunia, Physalis, Solanum. Anatomy non-C4 type (Cestrum, Datura, Lycium, Nicandra, Physalis, Solanum, Withania).
Many Solanaceae contain atropine and/or scopolamine, which are parasymphatolytica. The parasympathic system is suppressed, so there is an overactivity of the sympathatic system. People who need these remedies are constant alert and in stress.
Geography
Temperate to tropical. Absent only from cold regions, but with greatest diversity in Central and South America. X = 7–12(+).
Taxonomy
Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Solaniflorae; Solanales. Cronquist’s Subclass Asteridae; Solanales. APG (1998) Eudicot; core Eudicot; Asterid; Euasterid I; Solanales. Species 2000 (or more). Genera about 95; Acnistus, Anisodus, Anthocercis, Anthotroche, Archiphysalis, Althenaea, Atropa, Atropanthe, Benthamiella, Bouchetia, Brachistus, Browallia, Brugmansia, Brunfelsia, Calibrachoa, Capsicum, Cestrum, Chamaesaracha, Combera, Crenidium, Cuatresia, Cyphanthera, Cyphomandra, Datura, Deprea, Discopodium, Duboisia, Dunalia, Dyssochroma, Ectozma, Exodeconus, Fabiana, Grabowskia, Grammosolen, Hawkesiophyton, Heteranthia, Hunzikeria, Hyoscyamus, Iochroma, Jaborosa, Jaltomata, Juanulloa, Latua, Leptoglossis, Leucophysalis, Lycianthes, Lycium, Lycopersicon, Mandragora, Margaranthus, Markea, Melananthus, Mellissia, Merinthopodium, Metternichia, Nectouxia, Nicandra, Nicotiana, Nierembergia, Nothocestrum, Oryctes, Pantacantha, Parabouchetia, Pauia, Petunia, Phrodus, Physalis, Physochlaina, Plowmania, Protoschwenckia, Przewalskia, Quincula, Rahowardiana, Reyesia, Salpichroa, Salpiglossis, Saracha, Schizanthus, Schultesianthus, Schwenckia, Sclerophylax, Scopolia, Sessea, Sesseopsis, Solandra, Solanum, Streptosolen, Symonanthus, Trianaea, Triguera, Tubocapsicum, Vassobia, Vestia, Withania, Witheringia.
Economic uses
Products include potato and eggplant (Solanum spp.), and tomato (Lycopersicon). Other edible fruits from Physalis (cape gooseberry, strawberry tomato, jamberberry, sugar cherry, chinese lantern etc., according to the species and variety), Cymphomandra (tamarillo), Capsicum (sweet and chilli peppers), etc. Most produce poisonous alkaloids, and some are commercially important in this connection (Nicotiana, Hyoscyamus, Datura). Many cultivated ornamentals, e.g. Petunia, Lycium, Solanum, Cestrum, Solandra.
Quotations
And shrieks, like mandrakes’, torn out of the earth,
That living mortals, hearing them, go mad
(‘Romeo and Juliet’, iv.,3)
Atropa, too, that, as the beldams say,
Shows her black fruit to tempt and to betray
(Charlotte Smith, quoted by Ann Pratt, ‘Wild Flowers’ (1857))
The pipe, with solemn interposing puff,
Makes half a sentence at a time enough
(William Cowper, ‘Tobacco’)
When potatoes, leaves, or haulms are green,
To livestock must they ne’er be gi’en
(ancient anon, re. solanine poisoning.)
Fruits
Fruits originate from the female reproductive part of a flower the gynoecium and are ripenened and seed bearing ovaries (ovary). In the plant family Solanaceae the gynoecium is in most cases bicarpellate ( two carpels) with the following few exceptions:
1) Unicarpellate: in the genus Melananthus Walp. (1850) most probably?
2) 2 (3-4) Carpellate: in the genus Capsicum L.
3) 3-5 Carpellate: in Nicandra Adans (1763), in two species of Jaborosa Juss., and in Trianaea Planch. et Linden.
4) 4 Carpellate: in one species of Iochroma Benth. (1845) (Iochroma umbellatum (Ruiz. et Pavon.) Hunz.).
The number of locules in the ovary are normaly in accordance with the number of carpels (exceptions: Datura L. 2-carpellate and 4 locular due to false septa, some species in the Tribe Lycieae Hunz. such as in Grabowskia Schltdl. in its upper part, and Vassobia Rusby in part of the lower half.
As well as there is a relation between the number of carpels and the number of locules, there is also a relation between the number of ovules in the ovary and the number of seeds in the fruits. The ovule-orientation in Solanaceae is anatropous (Metternichia Mik., Nierembergia Ruiz. et Pav., etc., anacampylotropous (Phrodos Miers, Grabowskia Schltdl., Vassobia Rusby), hemitropous (Cestrum L. etc.) or hemicampylotropous (Capsicum L., Schizanthus Ruiz. et Pavon, Lycium L.etc.), being born on a rather fleshy placenta, usually many in each locule, sometimes few (in Grabowskia Schltdl. two pairs in each carpel, or one pair in some Lycium L. species), by exception a solitary ovule in Melananthus Walp., generally with similar size (exception: Grabowskia Schltdl. with two unequal elongated ovules in each locule, the upper one larger than the lower one).
The fruits in Solanaceae are in most cases berries or capsules (including pyxidia) and to a lesser extend drupes.
Berries
1) Subfamily CESTROIDEAE Schltdl.(only Cestrum L. and Latua Phil.)
2) Subfamily JUANULLOIDEAE (Hunz.) Hunz.(except Markea Rich. and Rahowardiana D'Arcy)
3) Subfamily SOLANOIDEAE Schltd. except:
a. Datura L. species (but one species havong a berry: Datura ceratocaula Ort.),
b. Oryctus S. Watson (capsule)
c. two species of Lycium L.(drupe)
d. Grabowskia Schltdl.(drupe),
e. tribe Hysocyameae Endl.(pyxidium)
4) Subfamily ANTHOCERCIDOIDEAE (G. Don) Tétényi (only the genus Duboisia R. Br.).
Capsules
1) Subfamily CESTROIDEAE Schltdl. (except Cestrum L., Latua Phil.)
2) Subfamily JUANULLOIDEAE (Hunz.) Hunz. (only Markea Rich. and Rahowardiana D'Arcy)
3) Subfamily SOLANOIDEAE Schltd. (only Datura L.[except D. ceratocaula Ort. ] and Oryctus S. Watson)
4) Subfamily SALPIGLOSSOIDEAE (Benth.) Hunz.
5) Subfamily SCHIZANTHOIDEAE (Miers) Hunz.
6) Subfamily ANTHOCERCIDOIDEAE (G. Don) Tétényi (except Duboisia R. Br.)
7) Tribe Hysocyameae Endl.(Pyxidium)
Drupes
1) Subfamily SOLANOIDEAE Schltd.,
a. tribe Lycieae Hunz. (two species of Lycium L.; Grabowskia Schltdl.)
b. tribe Solaneae Miers, subtribe Iochrominae (Miers) Hunz.