''. 1. flower; 2. flower in longitudinal section, without the petals; 3.
androecium; 4. ovary, in transverse section; 5. seed viewed from above; 6. seed in transverse section – note the curved embryo surrounding the endosperm; A. branch with leaves and flowers; B. stem with immature and mature fruit Nightshades can take the form of herbs,
shrubs,
trees,
vines and lianas, and sometimes
epiphytes. They can be
annuals,
biennials, or
perennials, upright or decumbent. Some have subterranean
tubers. They do not have
laticifers, nor
latex, nor coloured
saps. They can have a basal or terminal group of leaves or neither of these types. The
leaves are generally alternate or alternate to opposed (that is, alternate at the base of the plant and opposed towards the
inflorescence). The leaves can be herbaceous, leathery, or transformed into
spines. The leaves are generally
petiolate or subsessile, rarely sessile. They are frequently inodorous, but some are aromatic or fetid. The foliar lamina can be either simple or compound, and the latter can be either pinnatifid or ternate. The leaves have reticulated venation and lack a basal
meristem. The laminae are generally dorsiventral and lack secretory cavities. The
stomata are generally confined to one of a leaf's two sides; they are rarely found on both sides. of the
potato (Solanum tuberosum), Legend: 1 = sepals 2 = petals 3 = stamens 4 = superior ovary The
flowers are generally
hermaphrodites, although some are
monoecious,
andromonoecious, or
dioecious species (such as some
Solanum or
Symonanthus). They are most commonly
pollinated by
insects. The flowers can be solitary or grouped into terminal, cymose, or axillary inflorescences. The flowers are medium-sized, fragrant (
Nicotiana), fetid (
Anthocercis), or inodorous. The flowers are usually
actinomorphic, slightly
zygomorphic, or markedly zygomorphic (for example, in flowers with a bilabial corolla in
Schizanthus species). The irregularities in symmetry can be due to the
androecium, to the
perianth, or both at the same time. In the great majority of species, the flowers have a differentiated perianth with a calyx and
corolla (with five sepals and five petals, respectively) an androecium with five
stamens and two
carpels forming a
gynoecium with a superior
ovary (they are therefore referred to as pentamers and tetracyclic). The
stamens are
epipetalous and are typically present in multiples of four or five, most commonly four or eight. They usually have a hypogynous disk. The calyx is gamosepalous (as the sepals are joined forming a tube), with the (4)5(6) segments equal, it has five lobes, with the lobes shorter than the tube, it is persistent and often accrescent. The corolla usually has five petals that are also joined forming a tube. Flower shapes are typically rotate (wheel-shaped, spreading in one plane, with a short tube) or tubular (elongated cylindrical tube), campanulated, or funnel-shaped. The androecium has (2)(4)5(6) free stamens within its opposite sepals (they alternate with the petals). They are usually fertile or, in some cases (for example in Salpiglossideae) they have
staminodes. In the latter case, there is usually either one staminode (
Salpiglossis) or three (
Schizanthus). The anthers touch on their upper end forming a ring, or they are completely free, dorsifixed, or basifixed with poricide dehiscence or through small longitudinal cracks. The stamen's
filament can be filiform or flat. The stamens can be inserted inside the coralline tube or exserted. The plants demonstrate simultaneous microsporogenesis, the microspores are tetrad, tetrahedral, or isobilateral. The pollen grains are bicellular at the moment of dehiscence, usually open and angular. The gynoecium is bicarpelar (rarely three- or five-locular) with a
superior ovary and two
locules, which may be secondarily divided by false
septa, as is the case for Nicandreae and Datureae. The gynoecium is located in an oblique position relative to the flower's median plane. They have one
style and one
stigma; the latter is simple or bilobate. Each locule has one to 50 ovules that are anatropous or hemianatropous with axillar placentation. The development of the
embryo sack can be the same as for
Polygonum or
Allium species. The embryo sack's
nuclear poles become fused before
fertilization. The three antipodes are usually ephemeral or persistent as in the case of
Atropa. The
fruit can be a
berry as in the case of the tomato or wolfberry, or a
dehiscent capsule as in
Datura, or a
drupe. The fruit has
axial placentation. The capsules are normally septicidal or rarely loculicidal or valvate. The
seeds are usually endospermic, oily (rarely starchy), and without obvious hairs. The seeds of most Solanaceae are round and flat, about in diameter. The embryo can be straight or curved, and has two cotyledons. Most species in the Solanaceae have 2n=24
chromosomes, but the number may be a higher multiple of 12 due to
polyploidy. Wild
potatoes, of which there are about 200, are predominantly diploid (2 × 12 = 24 chromosomes), but triploid (3 × 12 = 36 chromosomes), tetraploid (4 × 12 = 48 chromosomes), pentaploid (5 × 12 = 60) and even hexaploid (6 × 12 = 72 chromosome) species or populations exist. The cultivated species
Solanum tuberosum has 4 × 12 = 48 chromosomes. Some
Capsicum species have 2 × 12 = 24 chromosomes, while others have 26 chromosomes.
Diversity of characteristics Despite the previous description, the Solanaceae exhibit a large morphological variability, even in their reproductive characteristics. Examples of this diversity include: • The number of carpels that form the gynoecium In general, the Solanaceae have a gynoecium (the female part of the flower) formed of two carpels. However,
Melananthus has a monocarpelar gynoecium, there are three or four carpels in
Capsicum, three to five in
Nicandra, some species of
Jaborosa and
Trianaea and four carpels in
Iochroma umbellatum. • The number of locules in the ovary The number of locules in the ovary is usually the same as the number of carpels. However, some species occur in which the numbers are not the same due to the existence of false septa (internal walls that subdivide each locule), such as in
Datura and some members of the Lycieae (the genera
Grabowskia and
Vassobia). • Type of ovules and their number The ovules are generally inverted, folded sharply backwards (anatropous), but some genera have ovules that are rotated at right angles to their stalk (campilotropous) as in
Phrodus,
Grabowskia or
Vassobia), or are partially inverted (hemitropous as in
Cestrum,
Capsicum,
Schizanthus and
Lycium). The number of ovules per locule also varies from a few (two pairs in each locule in
Grabowskia, one pair in each locule in
Lycium) and very occasionally only one ovule is in each locule as for example in
Melananthus. • The type of fruit The fruits of the great majority of the Solanaceae are berries or capsules (including pyxidia) and less often drupes. Berries are common in the subfamilies Cestroideae, Solanoideae (with the exception of
Datura,
Oryctus,
Grabowskia and the tribe Hyoscyameae) and the tribe Juanulloideae (with the exception of
Markea). Capsules are characteristic of the subfamilies Cestroideae (with the exception of
Cestrum) and Schizanthoideae, the tribes Salpiglossoideae and Anthocercidoideae, and the genus
Datura. The tribe Hyoscyameae has pyxidia. Drupes are typical of the Lycieae tribe and in Iochrominae. == Taxonomy ==