Orobanchaceae

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Orobanchaceae
OrobancheMinorIreland (2).jpg
Lesser broomrape ( Orobanche minor )
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Lamiales
Family: Orobanchaceae
Vent. [1]
Tribes [2]
Synonyms [3]
  • Cyclocheilaceae Marais (1981)
  • Nesogenaceae Marais (1981)

Orobanchaceae, the broomrapes, is a family of mostly parasitic plants of the order Lamiales, with about 90 genera and more than 2000 species. [4] Many of these genera (e.g., Pedicularis , Rhinanthus , Striga ) were formerly included in the family Scrophulariaceae sensu lato . [5] [6] [7] With its new circumscription, Orobanchaceae forms a distinct, monophyletic family. [7] From a phylogenetic perspective, it is defined as the largest crown clade containing Orobanche major and relatives, but neither Paulownia tomentosa nor Phryma leptostachya nor Mazus japonicus . [8] [9]

Contents

The Orobanchaceae are annual herbs or perennial herbs or shrubs, and most (all except Lindenbergia , Rehmannia and Triaenophora ) are parasitic on the roots of other plants—either holoparasitic or hemiparasitic (fully or partly parasitic). The holoparasitic species lack chlorophyll and therefore cannot perform photosynthesis.

Striga bilabiata Striga bilabiata MS4167.jpg
Striga bilabiata
Cistanche tubulosa Broomrape (Cistanche tubulosa) Negev.jpg
Cistanche tubulosa
Castilleja purpurea Castilleja purpurea.jpg
Castilleja purpurea
Pedicularis zeylanica Pedicularis zeylanica-Silent Valley-2016-08-13-001.jpg
Pedicularis zeylanica

Description

Orobanchaceae is the largest of the 20–28 dicot families that express parasitism. [10] Apart from a few non-parasitic taxa, the family displays all types of plant parasitism: facultative parasite, obligate parasite, hemiparasites, and holoparasites.

Roots and stems

Parasitic plants are attached to their host by means of haustoria, which transfer nutrients from the host to the parasite. Only the hemiparasitic species possess an additional extensive root system referred to as the lateral or side haustoria. In most holoparasitic species there is a swollen mass of short, bulky roots or one big swollen haustorial organ, which may be simple or composite, commonly called the terminal or primary haustorium. [11]

Plants are reduced to short vegetative stems, their alternate leaves are reduced to fleshy, tooth-like scales, and have multicellular hairs interspersed with glandular hairs. [12]

The hemiparasitic species (transferred from Scrophulariaceae) with green leaves are capable of photosynthesis, and may be either facultative or obligate parasites.

Flowers

The hermaphroditic flowers are bilaterally symmetrical and grow either in racemes or spikes or singly at the apex of the slender stem. The tubular calyx is formed by 2–5 united sepals. There are five united, bilabiate petals forming the corolla and they may be yellowish, brownish, purplish, or white. The upper lip is two-lobed, the lower lip is three-lobed. There are two long and two short stamens on slender filaments, inserted below the middle, or at the base of the corolla tube, alternating with the lobes of the tube. A fifth stamen is either sterile or lacking completely. The anthers dehisce via longitudinal slits. The pistil is one-celled. The ovary is superior. The flowers are pollinated by insects or birds (e.g., hummingbirds, as in Castilleja ).

Fruits

The fruit is a dehiscent, non-fleshy, 1-locular capsule with many very minute endospermic seeds. Fruits of Orobanchaceae are small and abundant and can produce between 10,000–1,000,000 seeds per plant. [13] These are dispersed by the wind over long distances, which increases their chances of finding a new host.

Taxonomy

The taxon was first described in 1799 by Étienne Pierre Ventenat as Orobanchoideae. The family name Orobanchaceae is a conserved name. [14] [15] Despite the similar morphological traits found in both Scrophulariaceae and Orobanchaceae, the latter is now considered a separate monophyletic taxon, on both molecular and mophological grounds. The 2016 APG IV system expanded Orobanchaceae to include genera previously placed in Scrophulariaceae, so that the family absorbed the former Lindenbergiaceae and Rehmanniaceae. [16] These two former families may be treated as tribes. [17] Molecular phylogenetic studies show that they are sisters to the other Orobanchaceae genera: [18] [19]

Orobanchaceae
Rehmannieae

Lindenbergia (Lindenbergieae) 

remaining Orobanchaceae

non-parasitic

Evolution

Development of the haustoria was a significant evolutionary event that allowed for the advancement of parasitic plants. The holoparasitic clade, Orobanche , delineates the first transition from hemiparasitism to holoparasitism within Orobanchaceae.[ citation needed ]

Plastid genes group all parasitic members of the Orobanchaceae, both hemiparasitic and holoparasitic, into a single monophyletic clade. [12] This phylogenetic relationship supports both the merging of the hemiparasitic members of the Scrophulariaceae with the Orobanchaceae, and also the hypothesis of one origin of hemiparasitism within the family, making it a key trait for delimiting clades and reconstructing evolutionary history. More recent phylogenetic analyses looking at nuclear orthologous genes across the major lineages of the Orobanchaceae have led to a highly resolved phylogeny that confirms these previous findings, adding that the common ancestor for parasitic species within the Orobanchaceae appeared approximately 38.6 million years ago. [20]

Once this parasitic habit evolved, holoparasitism is thought to have arisen several times independently, although the exact number is the subject of some debate [4] [12] . The plastid gene study, Young et. al (1999), states that holoparasitism evolved five times in different lineages: Once from Harveya, Lathraea and the traditional Orobanchaceae as well as the genus Alectra and the genus Striga. Importantly, more recent studies have found three origins of holoparasitism, with the origin at the genus Alectra belonging to the same lineage as that of Harveya, and Striga sometimes considered a hemiparasite as some species conduct photosynthesis  for parts of their life cycles [4] . These independent origins of holoparasitism illustrate homoplastic traits within a monophyletic group and highlight that while parasitism does act as a unifying trait for parts of the Orobanchaceae, it is a much more complex feature than originally thought. The repeated evolution of complete reliance on parasitism has significant impacts for understanding the mechanisms behind Orobanchaceous diversification.

This pattern of the evolution of holoparasitism does not support previous systematic conclusions based on the idea of an evolutionary series throughout the hemiparasitic to holoparasitic genera of the Scrophulariaceae and the Orobanchaceae [12] . Rather, these new conclusions emphasize the role that parasitism plays on diversification within the Orobanchaceae, highlighting the fact that different parasitic lineages arose in different evolutionary contexts, and that the internal systematics of the Orobanchaceae can be better understood as multiple branching points of differentiation rather than a linear gradient leading to one form of parasitism.

Genomics

The parasitism and its different modes have been suggested to have an impact on genome evolution, with increased DNA substitution rates in parasitic organisms compared to non-parasitic taxa. [21] For example, holoparasite taxa of Orobanchaceae exhibit faster molecular evolutionary rates than confamilial hemiparasites in three plastid genes. [22]

In a study comparing the rates of molecular evolution of parasitic versus non parasitic taxa for 12 pairs of angiosperm families — including Apodanthaceae, Cytinaceae, Rafflesiaceae, Cynomoriaceae, Krameriaceae, Mitrastemonaceae, Boraginaceae, Orobanchaceae, Convolvulaceae, Lauraceae, Hydnoraceae, and Santalaceae/Olacaceae —, parasitic taxa evolve on average faster than their close relatives for mitochondrial, plastid, and nuclear genome sequences. [23] Whereas Orobanchaceae fit to this trend for plastid DNA, they appear to evolve slower than their non parasitic counterpart in comparisons involving nuclear and mitochondrial DNA. [23]

Genera

As of February 2025, Plants of the World Online accepted 99 genera. [3] Three further genera are accepted by other sources, and are included in the following list.

Genera by life history trait

Orobanchaceae genera listed according to their life history trait.[ citation needed ]

Non-parasitic

Hemiparasitic

Holoparasitic

Distribution

The family Orobanchaceae has a cosmopolitan distribution, found mainly in temperate Eurasia, North America, South America, parts of Australia, New Zealand, and tropical Africa. The only exception to its distribution is Antarctica, though some genera may be found in subarctic regions. [25]

Ecology

This family has tremendous economic importance because of the damage to crops caused by some species in the genera Orobanche and Striga . They often parasitize cereal crops like sugarcane, maize, millet, sorghum, and other major agricultural crops like cowpea, sunflower, hemp, tomatoes, and legumes. Because of the ubiquitous nature of these particular parasites in developing countries, it is estimated to affect the livelihood of over 100 million people, killing 20 to 100 percent of crops depending on infestation. [26]

Some genera, especially Cistanche and Conopholis , are threatened by human activity, including habitat destruction and over-harvesting of both the plants and their hosts.

Research for this plant family can often be difficult due to its permit requirements for collection, travel, and research.

Notes

  1. ↑ Sometimes placed outside of Orobanchaceae as a sister-taxon.

References

  1. ↑ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III" (PDF). Botanical Journal of the Linnean Society. 161 (2): 105–121. doi: 10.1111/j.1095-8339.2009.00996.x . hdl: 10654/18083 . Archived from the original on 2013-06-30. Retrieved 2013-07-06.
  2. ↑ Stevens, Peter. "Angiosperm Phylogeny Website, version 13. Lamiales: Orobanchaceae". www.mobot.org. Archived from the original on 7 December 2010. Retrieved 20 December 2016.
  3. 1 2 "Orobanchaceae Vent." Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 2025-02-28.
  4. 1 2 3 McNeal, J. R.; Bennett, J. R.; Wolfe, A. D.; Mathews, S. (2013-05-01). "Phylogeny and origins of holoparasitism in Orobanchaceae". American Journal of Botany. 100 (5): 971–983. doi:10.3732/ajb.1200448. ISSN   0002-9122. PMID   23608647.
  5. ↑ dePamphilis, Claude W.; Young, Nelson D.; Wolfe, Andrea D. (1997-07-08). "Evolution of plastid gene rps2 in a lineage of hemiparasitic and holoparasitic plants: Many losses of photosynthesis and complex patterns of rate variation". Proceedings of the National Academy of Sciences. 94 (14): 7367–7372. Bibcode:1997PNAS...94.7367D. doi: 10.1073/pnas.94.14.7367 . ISSN   0027-8424. PMC   23827 . PMID   9207097.
  6. ↑ Young, Nelson D.; Steiner, Kim E.; dePamphilis, Claude W. (1999). "The Evolution of Parasitism in Scrophulariaceae/Orobanchaceae: Plastid Gene Sequences Refute an Evolutionary Transition Series". Annals of the Missouri Botanical Garden. 86 (4): 876. Bibcode:1999AnMBG..86..876Y. doi:10.2307/2666173. JSTOR   2666173. Archived from the original on 2020-07-18. Retrieved 2021-09-12.
  7. 1 2 Olmstead, Richard G.; Pamphilis, Claude W. de; Wolfe, Andrea D.; Young, Nelson D.; Elisons, Wayne J.; Reeves, Patrick A. (2001). "Disintegration of the Scrophulariaceae". American Journal of Botany. 88 (2): 348–361. doi: 10.2307/2657024 . ISSN   1537-2197. JSTOR   2657024. PMID   11222255.
  8. ↑ Xia, Zhi; Wang, Yin-Zheng; Smith, James F. (2009). "Familial placement and relations of Rehmannia and Triaenophora (Scrophulariaceae s.l.) inferred from five gene regions". American Journal of Botany. 96 (2): 519–530. doi:10.3732/ajb.0800195. ISSN   1537-2197. PMID   21628207.
  9. ↑ Tank, David C.; Wolfe, Andrea; Mathews, Sarah; Olmstead, Richard G. (2020-04-30). "Orobanchaceae E. P. Ventenant 1799:292 [D. C. Tank, A. D. Wolfe, S. Mathews, and R. G. Olmstead], converted clade name". In de Queiroz, Kevin; Cantino, Philip D.; Gauthier, Jacques A. (eds.). Phylonyms: A Companion to the PhyloCode. CRC Press. pp. 1749–1751. ISBN   978-0-429-82120-2.
  10. ↑ Kebab, E. (2013). Joel, Daniel M.; Gressel, Jonathan; Musselman, Lytton J. (eds.). Parasitic orobanchaceae parasitic mechanisms and control strategies. Berlin: Springer. ISBN   978-3-642-38146-1.
  11. ↑ Westwood, James H.; Yoder, John I.; Timko, Michael P.; dePamphilis, Claude W. (1 April 2010). "The evolution of parasitism in plants". Trends in Plant Science. 15 (4): 227–235. Bibcode:2010TPS....15..227W. doi:10.1016/j.tplants.2010.01.004. ISSN   1878-4372. PMID   20153240.
  12. 1 2 3 4 Young, N.D.; Steiner, K.E.; Claude, W. (1999). "The Evolution of Parasitism in Schrophulariaceae/Orobanchaceae: Plastid gene sequences refute an evolutionary transition series" (PDF). Annals of the Missouri Botanical Garden. 86 (4): 876–893. Bibcode:1999AnMBG..86..876Y. doi:10.2307/2666173. JSTOR   2666173.
  13. ↑ Molau, U. (1995). Parasitic Plants: Reproductive ecology and biology. London: Chapman and Hall. pp. 141–176.
  14. ↑ "Orobanchaceae Vent." International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens . Retrieved 2025-02-28.
  15. ↑ Ventenat, É. P. (1799). "Les Orobanchoïdes, Orobanchoideae". Tableau du règne végétal, selon la méthode de Jussieu. Vol. 2. Paris: de l'Imprimerie de J. Drisonnier. pp. 292–295. Retrieved 2025-02-28.
  16. ↑ Angiosperm Phylogeny Group (2016). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV". Botanical Journal of the Linnean Society. 181 (1): 1–20. doi: 10.1111/boj.12385 .
  17. ↑ Stevens, P.F. (2001 onwards). "Orobanchaceae". Angiosperm Phylogeny Website. Retrieved 2025-02-28.
  18. ↑ Li, Xi; Feng, Tao; Randle, Chris & Schneeweiss, Gerald M. (2019). "Phylogenetic Relationships in Orobanchaceae Inferred From Low-Copy Nuclear Genes: Consolidation of Major Clades and Identification of a Novel Position of the Non-photosynthetic Orobanche Clade Sister to All Other Parasitic Orobanchaceae". Frontiers in Plant Science. 10: 902. doi: 10.3389/fpls.2019.00902 . PMC   6646720 . PMID   31379896.
  19. ↑ Mortimer, Sebastian M. E.; Boyko, James; Beaulieu, Jeremy M. & Tank, David C. (2022). "Synthesizing Existing Phylogenetic Data to Advance Phylogenetic Research in Orobanchaceae". Systematic Botany. 47 (2): 533–544. doi:10.1600/036364422X16512564801560.
  20. ↑ Xu, Yuxing; Zhang, Jingxiong; Ma, Canrong; Lei, Yunting; Shen, Guojing; Jin, Jianjun; Eaton, Deren A. R.; Wu, Jianqiang (2022-04-14), Comparative genomics of orobanchaceous species with different parasitic lifestyles reveals the origin and stepwise evolution of plant parasitism, doi:10.1101/2022.04.13.488246 , retrieved 2025-12-19
  21. ↑ Haraguchi, Yoshihiro; Sasaki, Akira (1996-11-21). "Host–Parasite Arms Race in Mutation Modifications: Indefinite Escalation Despite a Heavy Load?". Journal of Theoretical Biology. 183 (2): 121–137. Bibcode:1996JThBi.183..121H. doi:10.1006/jtbi.1996.9999. ISSN   0022-5193. PMID   8977873.
  22. ↑ Young, Nelson D.; dePamphilis, Claude W. (2005-02-15). "Rate variation in parasitic plants: correlated and uncorrelated patterns among plastid genes of different function". BMC Evolutionary Biology. 5 (1): 16. doi: 10.1186/1471-2148-5-16 . ISSN   1471-2148. PMC   554776 . PMID   15713237.
  23. 1 2 Bromham, Lindell; Cowman, Peter F.; Lanfear, Robert (1 January 2013). "Parasitic plants have increased rates of molecular evolution across all three genomes". BMC Evolutionary Biology. 13 (1): 126. Bibcode:2013BMCEE..13..126B. doi: 10.1186/1471-2148-13-126 . ISSN   1471-2148. PMC   3694452 . PMID   23782527.
  24. 1 2 3 Stevens, P.F. (2001 onwards). List of Genera in Orobanchaceae. Angiosperm Phylogeny Website. Retrieved 2025-02-28.
  25. ↑ Watson, David M. (October 13, 2009). "Parasitic plants as facilitators: more Dryad than Dracula?". Journal of Ecology. 97 (6): 1151–1159. Bibcode:2009JEcol..97.1151W. doi: 10.1111/j.1365-2745.2009.01576.x . S2CID   84242604.
  26. ↑ Westwood, James H.; dePamphilis, Claude W.; Das, Malay; Fernández-Aparicio, Mónica; Honaas, Loren A.; Timko, Michael P.; Wafula, Eric K.; Wickett, Norman J.; Yoder, John I. (April–June 2012). "The Parasitic Plant Genome Project: New Tools for Understanding the Biology of Orobanche and Striga". Weed Science. 60 (2): 295–306. doi:10.1614/WS-D-11-00113.1. ISSN   0043-1745. S2CID   26435162.
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