Primulaceae

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Primulaceae
Primula vulgaris 'rubra'
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Ericales
Family: Primulaceae
Batsch ex Borkh., nom. cons.[1][2]
Type genus
L.
Synonyms[3]
  • Myrsinaceae R. Br. Prodr. Fl. Nov. Holland. 532. 1810 [27 Mar 1810] (as "Myrsineae") (1810)
  • Theophrastaceae

The Primulaceae

perennial though some species, such as scarlet pimpernel, are annuals
.

Previously one of three families in the

sensu stricto or s.s.) then became subfamily Primuloideae, and one genus (Maesa
) was raised to the rank of a separate subfamily, making four in all.

Description

Botanical drawing of Primula officinalis Jacquin. Legend: (A) the whole plant; (2) and (3) vertical cross-sections of the flower; (4) stamen; (5) horizontal cross-section of flower showing the calyx around the flower crown and stigma; (6) the stigma; (7) cross section through the ovary; (8) calyx; (9) seed; (10) cross section of seed[4]

The family shares a number of characteristics, including

bitegmic (two layered) ovules and nuclear endosperm formation.[clarification needed][5]

Stems

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).[6][7]

Leaves

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.[6][7]

Flowers

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.[8]

The calyx has 4 to 9 lobes and persists after flowering.[7] They are grouped in unbranched, indeterminate clusters such as racemes, spikes, corymbs or umbels.[6]

Reproductive anatomy

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).[8]

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.[6]

Taxonomy

History

The taxonomic history of Primulaceae has been long and complex. The

Borkhausen (1797).[a][9] Some earlier authors[clarification needed] attributed the name to Ventenat (1799), as Primulaceae Vent.,[10] who described the Primulacées,[11] but Batsch had precedence.[2]

Sapotae, including Myrsine, these being the three main lineages in modern understanding.[15]

The most complete treatment of the Primulaceae

genera, was by Pax and Knuth in 1905 in the Engler system. They divided the family into five tribes (and several subtribes); Androsaceae, Cyclamineae, Lysimachieae, Samoleae and Corideae.[16][17] Many systems since have lacked consistency, but generally recognised two major groups as either tribes or subfamilies, the Lysimachieae and Primuleae (the Androsaceae of Pax and Knuth), with the largest genera being Primula, Lysimachia and Androsace.[18][17]
In the
synapomorphic.[19] His circumscription of Primulaceae included about 800 species.[20]

Molecular phylogenetics

These three families were referred to as the primuloid families.

Maesaceae, but also that Primulaceae were probably paraphyletic.[21][22][5]

In the first consensus taxonomic classification, the

sensu stricto (s.s.) consisted of three groups: The Primulae, including Primula, the largest genus; the Androsaceae, including Androsace, the second largest genus; together with a small third group containing Soldanella, Hottonia, Omphalogramma and Bryocarpum.[18]

The APG third classification system (APG III, 2009) discussed all the taxonomic challenges arising from the phylogenetic studies, and placed all primuloid genera into one large Primulaceae s.l., corresponding to Cronquist's Primulales. They stated that "The biggest problem for APG III was the question of how to treat Primulaceae and their immediate relatives, a closely related group that in the past has often been recognized as a separate order". The decision to treat all genera as a single family was based on the observation that the new circumscriptions had little in the way of

apomorphies, but the entire group had numerous synapomorphies and were easy to recognise. This resulted in an Ericales with 22 families.[27] Consequently, the four primuloid families were reduced to the rank of subfamilies within Primulaceae s.l.[29]

Phylogeny

Primulaceae s.l. sensu APG III form part of the speciose (species rich) Asterid order Ericales s.l., with about 12,000 species and 22

euasterids.[31] The phylogenetic structure of Ericales, as shown in the following cladogram, consists of seven major suprafamilial clades (e.g. balsaminoids, styracoids) and a group of "core" Ericales. Within the eracalean families, Primulaceae s.l. is shown as a sister group to Ebenaceae, and both are sister to Sapotaceae. These three families make up the primuloid clade.[30]

Evolution and biogeography

The

basal group, to 70 mya for the Theophrastoideae.[30]

The primuloids probably originated in a shared

Nearctic.[30]

Subdivision

The three former families of the Primulales, together with the segregated Maesaceae, have been

sensu lato (s.l.) The two uniting features of this family are a free central placenta and one stamen opposite each of the corolla lobes.[2][33][27]
The cladogram below shows the infrafamilial phylogenetic relationships, together with the subfamilial crown ages. Maesoideae forms the basal group, while Primuloideae and Myrsinoideae are in a sister group relationship.[33][8][29][30]

Primulaceae 
s.l.

Maesoideae

24.1mya

Christenhusz et al. (2016, 2017) list 2,790 species and 53 genera, varying from 1 in Maesoideae to 38 in Myrsinoideae, with 8 in Theophrastoideae and the remaining 6 in Primuloideae.[34][32] Byng (2014)[29] and Plants of the World Online list 55 accepted genera.[3][33][8][29][30] The generic limits of Myrsinoideae are not fully resolved and the status of a number of genera is under revision.[35]

Subfamilies

Flowers and leaves of Maesa lanceolata
Maesa lanceolata
Maesoideae (A. DC.) A. DC.
Main article:
Maesoideae

Maesoideae is a

panicles. Maesa has about 100 species, and is distributed in both tropical and subtropical regions of the Old World, ranging from East Africa to Japan.[5]

Once included in the Primulaceae tribe Samoleae, it has most commonly been considered as part of family Myrsinaceae, till segregated into its own family[24] and then submerged as a Primulaceae s.l. subfamily. It has characteristics that distinguish it from Myrsinaceae and forms the basal group of the clade as sister to all other subfamilies.[5]

Flowers and leaves of Myrsine africana
Myrsine africana
Myrsinoideae Burnett
Main article: Myrsinoideae

The relatively large Myrsinoideae, has been treated as a number of tribes, e.g. Ardisieae and Myrsineae, and more recently Lysimachiaeae, a transfer from Primulaceae s.s. Ardisieae and Myrsineae represent the woody clades within the subfamily.[30] Within the Myrsinoideae, the genera represented by the restricted Myrsinaceae s.s., prior to the transfers from the then Primulaceae, form a distinct clade.[35] Genera in Lysimachiaeae are Trientalis, Anagallis, Glaux, Lysimachia, Asterolinon and Pelletiera. Coris had its own tribe within Primulaceae s.s., Corideae, but its molecular affinities led to its transfer to Myrsinoideae. Similarly, Ardisiandra was the tribe Ardisiandreae and Cyclamen the tribe Cyclamineae.[5]

Flowers of Primula veris
Primula veris
Primuloideae Burnett
Main article: Primuloideae

The subfamily is characterised by

campanulate or hypocrateriform corolla, imbricate corolla aestivation, isodiametric corolla epidermal cells, leaves almost always forming a basal rosette, and ovules rarely immersed in the placenta. In addition they often have syncolpate or sometimes polycolpate pollen, without margo.[5]

Subdivision has included the tribes Androsaceae and Primulae. Takhtajan (1997) gives the four genera of Androsaceae as Androsace (including Douglasia), Vitaliana, Stimpsonia and Pomatosace, and the ten genera of Primulae as Omphalogramma, Bryocarpum, Primula, Dionysia, Cortusa, Kauffmannia, Hottonia, Srediskya, Dodecatheon and Soldanella.[10]

In contrast Kallersjo et al. (2000) place all genera in Primulae, and list thirteen in all: Androsace, Douglasia, Omphalogramma, Soldanella, Dodecatheon, Cortusa, Primula, Dionysia, Vitaliana, Hottonia, Bryocarpum, and Pomatosace. These two (or one) tribes represent the remaining genera in Primuloideae (Primulaceae s.s.) following redistribution among the Primulales on molecular grounds. The 600 species mainly belong to Androsace and Primula and belong to the mountainous regions of Europe and Asia (mainly China).[5]

Specimen of Theophrasta jussieui
Theophrasta jussieui
Theophrastoideae A. DC.
Main article: Theophrastoideae

Theophrastoideae consist of a relatively small subfamily, whose flowers are

berries. The ovary is superior, and the corolla is often tubular. The eight genera are confined to South and Central America. Samolus is a distinct genus, being sister to all other Theophrastoideae. Previously it formed its own tribe, Samoleae within Primulaceae s.s., and in some systems, its own family, Samolaceae, but was subsequently transferred to Theophrastoideae.[5]

Etymology

The Primulaceae are named for their nominative and type genus, Primula. Linnaeus used this name to reflect its place among the first flowers of spring, given the primrose's vernacular Latin name of primula veris (lit. 'little first of spring'), primula (feminine diminutive primus, first + veris (genitive ver, spring).[11]

Distribution and habitat

Distribution is cosmopolitan.[30]

Cultivation

The British National Collection of Double Primroses is held at Glebe Garden, at North Petherwin, in North Cornwall.[36][37][38]

Notes

  1. ^ "More additions affectingconserved familial names are from Batsch (1794), which is to be considered as the place for valid publication of Melanthiaceae and Primulaceae, both accepted and conserved with the authorship of'Batsch ex Borkh. 1797' but validly published in 1794 by a reference in the introduction of that book to the corresponding descriptions in Batsch (1786)"[2]
  2. ^ Ericales has 21 or 22 families, depending on whether Sladeniaceae is recognised as separate from, or submerged in Pentaphylacaceae[30]

References

  1. ^ a b Batsch 1793–1794, ii 395.
  2. ^ a b c d APG IV 2016.
  3. ^ a b POWO 2021.
  4. ^ Thomé 1903.
  5. ^ a b c d e f g h i j Kallersjo et al 2000.
  6. ^ a b c d Anderberg 2004.
  7. ^ a b c Xu & Chang 2017.
  8. ^ a b c d e f g Anderberg et al 2002.
  9. ^ Borkhausen 1797, p. 240.
  10. ^ a b c Takhtajan 1997, p. 200.
  11. ^ a b Ventenat 1799, vol. ii pp. 289–291.
  12. ^ Linnaeus 1753.
  13. ^ Jussieu 1789, p. 93.
  14. ^ Jussieu 1789, p. 95.
  15. ^ Jussieu 1789, p. 151.
  16. ^ Pax & Knuth 1905.
  17. ^ a b c Martins et al 2003.
  18. ^ a b Schneeweiss et al 2004.
  19. ^ a b Mast et al 2001.
  20. ^ Cronquist 1988, pp. 357–359.
  21. ^ Anderberg & Ståhl 1995.
  22. ^ Anderberg et al 1998.
  23. ^ APG I 1998.
  24. ^ a b Anderberg et al 2000.
  25. ^ Stahl 2004a.
  26. ^ Ståhl 2010.
  27. ^ a b c APG III 2009.
  28. ^ APG II 2003.
  29. ^ a b c d Byng 2014.
  30. ^ a b c d e f g h Rose et al 2018.
  31. ^ Schonenberger et al 2005.
  32. ^ a b Christenhusz et al 2017, p. 494.
  33. ^ a b c Soltis et al 2018.
  34. ^ Christenhusz & Byng 2016.
  35. ^ a b Yan et al 2019.
  36. ^ Byfield 2015.
  37. ^ Stone 2021.
  38. ^ Cornwall Gardens Trust 2021.

Bibliography

Books

  • ISBN 978-0-9929993-1-5
    .
  • ISBN 978-0-226-52292-0
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  • S2CID 12809916
    .
  • Bhattacharyya, Bharati (2005). Systematic botany. Alpha Science International. pp. 216–218.
    ISBN 9781842652510
    .
  • ISBN 9780893273323. (Available here at Internet Archive
    )
  • Datta, Subhash C. (1988). "Primulaceae". Systematic botany. New Age Intl. pp. 387–388.
    ISBN 9788122400137
    .
  • Judd, W.S.; Campbell, C.S.; Kellogg, E.A.; Stevens, P.F.; Donoghue, M.J. (2002). "Ericales". Plant Systematics: A Phylogenetic Approach (2nd ed.).
    ISBN 978-0-87893-403-4
    .
  • ISBN 978-0-226-44175-7
    .
  • ISBN 978-0-231-10098-4.(Available here at Internet Archive
    )
  • ISBN 9781316790656
    .
  • Xu, Zhenghao; Chang, Le (2017). "2. Primulaceae". Identification and Control of Common Weeds. 3 vols. Vol. 3 (3rd ed.).
    ISBN 978-981-10-5403-7
    .

Chapters

Historical sources

Articles

Ericales

Maesoideae

Myrsinoideae

Primuloideae

Theophrastoideae

APG

Websites

External links

Wikispecies has information related to Primulaceae.
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