|Primula vulgaris 'rubra'|
Batsch ex Borkh., nom. cons.
The Primulaceae, commonly known as the primrose family (but not related to the evening primrose family), are a family of herbaceous and woody flowering plants including some favorite garden plants and wildflowers. Most are perennial though some species, such as scarlet pimpernel, are annuals. It includes the former families Myrsinaceae, Theophrastaceae and Maesaceae.
Primulaceae is one of 22 families in the order Ericales. Formerly, this order included some closely related families: Myrsinaceae (myrsine family), Theophrastaceae and Maesaceae (which contained only one genus, Maesa). However, morphological and molecular data strongly support their membership in the primuloid clade, which corresponds to the Primulales order in the 1981 Cronquist system. The four families have been re-circumscribed into a more broadly defined family referred to as Primulaceae s. l. The two uniting features of this clade are a free central placenta and one stamen opposite each of the corolla lobes.
- Aegiceras Gaertn.
- Amblyanthopsis Mez
- Amblyanthus A.DC.
- Androsace L.
- Antistrophe A.DC.
- Ardisia Sw.
- Ardisiandra Hook. f.
- Badula Juss.
- Bryocarpum Hook. f. & Thomson
- Conandrium (K.Schumann) Mez
- Coris L.
- Cybianthus Mart.
- Cyclamen L.
- Dionysia Fenzl
- Discocalyx Mez
- Elingamita G.T.S. Baylis
- Embelia Burm.f.
- Emblemantha B.C.Stone
- Fittingia Mez
- Geissanthus Bentham & Hooker
- Heberdenia Banks ex A.DC.
- Hottonia Boehr. ex L.
- Hymenandra A.DC.
- Jacquinia L.
- Kaufmannia Regel
- Labisia Lindley
- Loheria Merrill
- Lysimachia Tourn. ex L.
- Maesa Forssk.
- Mangenotiella M.Schmid
- Microconomorpha (Mez) Lundell
- Monoporus A.DC.
- Myrsine L.
- Neomezia Votsch
- Omphalogramma Franch.
- Oncostemum A. de Jussieu
- Parathesis J.D.Hooker f.
- Pleiomeris A.DC.
- Primula L.
- Sadiria Mez
- Samolus L.
- Soldanella L.
- Solonia Urban
- Stimpsonia C.Wright ex A.Gray
- Stylogyne A.DC.
- Systellantha B.C.Stone
- Tapeinosperma Hook.f.
- Theophrasta L.
- Trientalis L.
- Vegaea Urban
- Votschia B.Ståhl
- Wallenia Sw.
Primulaceae are mostly herbaceous, having no woody stem, except that some form cushions (spreading mats a few inches high) and their stems are stiffened by lignin. The stems can grow upright (erect) or spread out horizontally and then turn upright (decumbent).
Leaves are simple, being directly attached to the stem by a petiole (stalk), but unlike the leaves of most flowering plants they have no stipules. The petiole is short or the leaf tapers gradually towards the base. Leaf arrangement is typically alternate but some are opposite or whorled, and there is generally a rosette at the base of the stem. The edges are toothed (dentate) or sawtoothed. New leaves in the bud are usually involute (rolled towards the upper surface) or conduplicate (folded upwards), but a few species roll downwards.
Each flower is bisexual, having both stamens and carpels. They have radial symmetry; the petals can be separate or partially or fully fused together to form a tube-shaped corolla that opens up at the mouth to form a bell-like shape (as in item 8 in the figure) or a flat-faced flower. In most of the families of Ericales, stamens alternate with lobes, but in Primulaceae there is a stamen opposite each petal.
The fruit of Primulaceae begins as an ovary and inside it are the future seeds (ovules). These are attached to a central axis without any partitions between them (an arrangement called free central placentation; see item 7 in the figure), and they are bitegmic (having a double protective layer around each ovule). Unlike in most other families of Ericales, both layers form the opening at the top (the micropyle).
Seeds and fruit
As seeds develop, an endosperm grows around the embryo through free division of nuclei without forming walls (nuclear endosperm formation). The embryo forms a pair of short, narrow cotyledons (item 10 in the figure). Usually multiple seeds are in a capsule that is carried on a straight stalk (pedicel or scape). After it matures, it splits apart, releasing the seeds ballistically.
Soldanella alpina, Androsace helvetica & Androsace chamaejasme
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