Droseraceae Salisb.

First published in Parad. Lond. 2: ad t. 95. 1808 [1 Feb 1808] (1808)nom. cons.
This family is accepted

Descriptions

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit
Carnivorous herbs
Morphology Leaves
Leaves alternate, forming basal rosettes, rarely alternate or whorled on short stems,, simple, with sticky glandular trichomes (appearing as tentacles) present on lamina and petiolesmargins entire; stipulate (can be scaly or leafy)
Morphology Reproductive morphology Inflorescences
Inflorescence terminal, cymose, paniculate, racemose, rarely solitary
Morphology Reproductive morphology Flowers
Flowers actinomorphic, bisexual, ebracteate; sepals (4-)5-8(-12), imbricate, persistent; petals (4-)5-8(-12), polypetalous, alternating with short-lived sepals; stamens (4-)5(-20),   free from and alternating with perianth, anthers extrorse, longitudinally dehiscent; ovary superior, syncarpous, carpels (2-)3(-5); styles (2-)3(-5), much- divided
Morphology Reproductive morphology Fruits
Fruits loculicidal capsules
Morphology Reproductive morphology Seeds
Seeds  3 to numerous.
Note
Notes on delimitation: Regularly allied with other carnivorous plant groups such as the Nepenthaceae and Sarraceniaceae. Currently placed in the Caryophyllales in a group which includes the extra-Neotropical Nepenthaceae, the monotypic (and recently included member of the Droseraceae) Drosopyllaceae, plus Dioncophyllaceae and Ancistrocladaceae (APG III & Stevens 2008). Number of genera: 1: Drosera with ca. 20 species. Known as the 'Sundews'.
Distribution
Have adapted to grow in wet areas with very few available nutrients - such as bogs and swamps. Found from sea-level to altitudes over 3,000m throughout the Neotropics. Native.
Diagnostic
Key differences from similar families: The Neotropical representatives of the Sarraceniaceae, Heliamphora Benth, have highly modified leaves called 'amphores' which are employed as insect-traps. Distinguishing characters (always present): Modified, insectivorous leaves with enzyme-secreting, tentacle-like glandular trichomes.
[NTK]

Droseraceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:1. 1954

Morphology General Habit
Herbs, often stemless with rosettes of leaves, the latter usually covered with sticky stipitate glands which entrap insects
Morphology Reproductive morphology Flowers
Flowers actinomorphic, hermaphrodite, in usually simple circinate cymes
Morphology Reproductive morphology Flowers Calyx
Sepals 5–4, more or less connate at the base, imbricate, persistent
Morphology Reproductive morphology Flowers Corolla
Petals 5, hypogynous, very rarely perigynous, nervose
Morphology Reproductive morphology Flowers Androecium
Stamens 4–20, often 5, hypogynous, free or rarely united at the base; anthers 2-celled, extrorse, opening by longitudinal slits
Morphology Reproductive morphology Flowers Gynoecium
Ovary free, 1-celled, with parietal or subbasal placentas; ovules many or rarely few; styles 3–5, mostly free
Morphology Reproductive morphology Fruits
Fruit a loculicidal capsule
Morphology Reproductive morphology Seeds
Seeds numerous, with fleshy endosperm; embryo straight; cotyledons short
[FWTA]

Droseraceae, J.R. Laundon. Flora of Tropical East Africa. 1959

Morphology General Habit
Insectivorous herbs
Morphology Leaves
Leaves in whorls or spirally arranged
Morphology Reproductive morphology Flowers
Flowers in racemes or cymes or occasionally solitary, regular, hypogynous, hermaphrodite
Morphology Reproductive morphology Flowers Calyx
Sepals 4–8, imbricate, basally connate
Morphology Reproductive morphology Flowers Corolla
Petals 4–8, imbricate, free, convolute
Morphology Reproductive morphology Flowers Androecium
Stamens 5–20 in 1 or more whorls
Morphology Reproductive morphology Flowers Gynoecium
Ovary superior, syncarpous, 3–5-carpellary, unilocular; styles 3–5, free or somewhat united, simple or branched; ovules numerous, on 3–5 parietal placentas or a free-basal placenta
Morphology Reproductive morphology Fruits
Fruit a loculicidal capsule
Morphology Reproductive morphology Seeds
Seeds small, with endosperm
[FTEA]

Droseraceae, J. R. Laudon. Flora Zambesiaca 4. 1978

Morphology General Habit
Annual or perennial insectivorous herbs
Morphology Leaves
Leaves in whorls or alternate, frequently in basal rosettes; lamina with glandular excrescences; stipules usually present
Morphology Reproductive morphology Flowers
Flowers in racemes or cymes or occasionally solitary, actinomorphic, hypogynous, bisexual
Morphology Reproductive morphology Flowers Calyx
Sepals 4–8, basally connate, imbricate
Morphology Reproductive morphology Flowers Corolla
Petals 4–8, free, imbricate
Morphology Reproductive morphology Flowers Androecium
Stamens 5–20 in 1 or more whorls; filaments free or united at the base; anthers 2-locular, dehiscing by longitudinal slits
Morphology Reproductive morphology Flowers Gynoecium
Ovary superior, syncarpous, 3–5-carpellary, 1-locular; styles 3–5, free or more or less united, simple or branched; ovules numerous, on 3–5 parietal placentas or a free basal placenta
Morphology Reproductive morphology Fruits
Fruit a loculicidal capsule
Morphology Reproductive morphology Seeds
Seeds small, with endosperm
[FZ]

Gemma Bramley, Anna Trias-Blasi & Richard Wilford (2023). The Kew Temperate Plant Families Identification Handbook. Kew Publishing Royal Botanic Gardens, Kew

Recognition
Characters of similar families: Byblidaceae (in New Guinea and Australia only): stipules absent, stalked glands of leaves entirely colourless (lacking red head), glands immobile, leaves not circinnate. Roridulaceae (South Africa only): stipules absent, leaf and stem glands immobile, leaves not circinnate. Drosophyllaceae (in the western Mediterranean): shrubby, leaves reverse circinnate, glandular hairs immobile.
Morphology General Habit
Carnivorous herbs, short-lived or perennial, with underground rootstocks, forming sessile rosettes or aerial stems, rarely verticillate and/or twining (Australia)
Morphology General Sap
Sap absent
Morphology General Hair
Hairs glandular conspicuous and dense on the adaxial leaf-blades, short and immobile and long and mobile, attracting and trapping prey; stalked, the head usually red, forming a sphere of mucilage (hairs absent in Dionaea and Aldrovanda, which have leaf-blades that are mechanical snap-traps instead)
Morphology Leaves Stipules
Stipules adaxial-Leaves simple, circinnate, alternate or spiral, margins entire
Morphology Reproductive morphology Inflorescences
Inflorescences appearing axillary, or terminal, usually racemoid cymes, rarely subpaniculate or single-flowered
Morphology Reproductive morphology Flowers
Flowers bisexual, actinomorphic, small or large, white, red or yellow; perianth 5-merous, sepals 5, free; petals 5, free; stamens usually 5(4–20) free, 2–4-locular, dehiscence longitudinal, pollen in tetrads; ovary superior, unilocular, ovules numerous, styles 3–5 sometimes branched
Morphology Reproductive morphology Fruits
Fruit dry, dehiscent capsule; seeds numerous, minute.
Distribution
A temperate and tropical family of 3 genera and about 250 species. Dionaea (SE USA), the Venus flytrap, is terrestrial and has mechanical traps, as does the aquatic, free-floating, rootless widespread and threatened Old World (Eurasia to Australia) Aldrovanda (both of these genera are monotypic). Drosera is most diverse in Brazil and SW Australia, with a secondary centre in the Cape of South Africa.
Ecology
In temperate areas, the species usually occur in nutrient-poor bogs.
Note
Leaves circinnate, alternate or spiral, often in sessile rosettes, rarely in verticils, covered in sessile and stalked glandular hairs with red centres in the middle of mucilage globules. (Dionaea and Aldrovanda lack hairs but the two halves of the leaf blade close swiftly when triggered).
Description Author
Martin Cheek
[KTEMP-FIH]

Sources

  • Flora Zambesiaca

    • Flora Zambesiaca
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Flora of Tropical East Africa

    • Flora of Tropical East Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Flora of West Tropical Africa

    • Flora of West Tropical Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0
  • Neotropikey

    • Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics.
    • http://creativecommons.org/licenses/by-nc-sa/3.0
  • The Kew Temperate Plant Families Identification Handbook

    • The Kew Temperate Plant Families Identification Handbook
    • http://creativecommons.org/licenses/by-nc-sa/3.0