Aristolochiaceae Juss.

Aristolochiaceae, B. Verdcourt. Flora of Tropical East Africa. 1986

Morphology General Habit

Herbs, shrubs or climbers, those with woody stems mostly with characteristic broad medullary rays

Morphology Leaves

Leaves alternate, simple, entire or lobed, often cordate, palmately nerved, petiolate, exstipulate

Morphology Reproductive morphology Flowers

Flowers hermaphrodite , epigynous, solitary, racemose or in fascicles, sometimes on the old wood at base, terminal or axillary, with or without bracts, regular or irregular

Morphology Reproductive morphology Flowers Calyx

Calyx usually enlarged and petaloid, basally tubular or campanulate, with either a symmetrically 3-lobed limb or unilateral and entire or lobed, often highly coloured and foetid

Morphology Reproductive morphology Flowers Corolla

Petals usually absent but well developed in Saruma and vestigial in >i>Asarum

Morphology Reproductive morphology Flowers Androecium

Stamens usually 6 or more in 1 or 2 series around the apex of the ovary or adnate to the stylar column forming a gynostegium, the filaments short, thick, free or scarcely distinguished from the column; anthers with 2 thecae, opening extrorsely by dorsal slits, free or united with style; pollen subspherical and inaperturate

Morphology Reproductive morphology Flowers Gynoecium

Ovary inferior or rarely half-inferior, completely or partially 4–6-locular, with parietal or axile placentas, the styles united into a column; stigma 3–many-lobed (in >i>Saruma, however, the carpels are free); ovules numerous in 2 series in each locule, anatropous, horizontal or pendulous

Morphology Reproductive morphology Fruits

Fruit a capsule, often opening from the base upwards or less often indehiscent

Morphology Reproductive morphology Seeds

Seeds numerous, usually flat, with copious horny or fleshy endosperm and minute embryo

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

Morphology General Habit

Climbing shrubs, or rarely dwarf and erect; stems of the woody species in cross-section showing broad medullary rays; roots often medicinal

Morphology Leaves

Leaves petiolate, alternate, exstipulate, simple, mostly entire

Morphology Reproductive morphology Flowers

Flowers solitary or racemose, axillary or in clusters on the older wood, pedicellate, hermaphrodite, zygomorphic or rarely actinomorphic

Morphology Reproductive morphology Flowers Perianth

Perianth single, often enlarged and petaloid, variously produced above the ovary, often tubular, the limb either symmetrically 3-lobed, or unilateral and entire or lobed, usually highly coloured and foetid

Morphology Reproductive morphology Flowers Androecium

Stamens 6-∞ , in 1–2 series around the apex of the ovary or stylar column; filaments short, thick, free or scarcely distinguishable from the column; anthers free or adnate, with 2 parallel cells, extrorse, opening longitudinally

Morphology Reproductive morphology Flowers Gynoecium

Ovary inferior or rarely semi-superior, 4–6-celled or imperfectly celled; styles thick, short, united into a column, divided into 3–8 stigmatic lobes; ovules numerous in each cell

Morphology Reproductive morphology Fruits

Fruit capsular or rarely indehiscent, sometimes dehiscing from the base upwards and hanging like an inverted parachute

Morphology Reproductive morphology Seeds

Seeds numerous, often immersed in the pulpy endocarp, 3-sided or flattened, raphe sometimes thickened or winged; endosperm copious, fleshy; embryo small

Edwards, S. (2009). Neotropical Aristolochiaceae.

Morphology

Description

Lianas or vines, rarely herbs or shrubs, usually rhizotamous, odorous. Stems terete often with corky bark on older stems. Leaves alternate , distichous , simple , entire , cordate to linear with sagittate or hastate lobes, occasionally 3- lobed , often palmately veined ; pseudostipules sometimes present. Inflorescences fasciculate , racemose or rhipidia or helicoidal cymes, axillary or cauliflorous . Flowers bisexual , zygomorphic , protogynous; perianth formed of 3 fused, petal -like sepals, often 'S' or 'U'-shaped, inflated with utricle at base, narrowing to tube, expanding into 1-3 lobed lamina limb at apex , purple, red, yellow or pink, often mimicking rotting flesh; petals absent; stamens 5-6, single whorl fused to styles to form (3,5)6-(12) lobed gynostemium; ovary inferior, twisted, carpels 5-6, syncarpous, locules 5-6, placentation submarginal, ovules usually numerous. Fruits dehiscent capsules, septicidally or septifragally, acropetally (hexandrous Aristolochia L.) or basipetally (pentandrous Aristolochia and Isotrema Raf.), opening into a basket-like shape. Seeds usually numerous, winged or with sticky aril ; embryo small, weakly dicotyledonous; endosperm abundant, oily, sometimes starchy.

Distribution

Distribution in the Neotropics

• Aristolochia: Throughout the Neotropics (subsect. Pentandrae Duch. Mexico and Caribbean; subsect. Hexandrae (Duch.) F.González throughout the Neotropics).
• Isotrema: Central America.

Diagnostic

Distinguishing characters (always present)

• Alternate leaves.
• Inferior ovary.
• Zygomorphic, aromatic often foetid flowers (can be actinomorphic in other geographical areas).
• Capsular fruit, usually numerous, winged or arillate seeds.

Useful tips for generic identification

• Although the genus Isotrema was split from Aristolochia by Rafinesque in 1819 botanists have disagreed as to whether these are two genera or one. The debated synonymy between the genera Aristolochia and Isotrema reflects their morphological similarities.
• The most visually obvious characteristic setting Isotrema apart from Aristolochia is its 3-lobed calyces, Aristolochia having 1-2-lobed calyces.

General Description

General notes

• Plants in the family Aristolociaceae contain aristolochic acids. These have been used in traditional Chinese medicines e.g. Isotrema manshuriense (Kom.) H. Huber or in Chinese Mu Tong or Guan Mu Tong for the treatment of mouth ulcers, oedema, urinary problems and arthritis. The use of I. manshuriense (Kom.) H. Huber has been banned in Europe since 2001 and in China since 2003 due to the aristolochic acids being found to be carcinogenic, nephrotoxic and mutagenic.
• In European herbal medicine Aristolochia clematitis L. was traditionally used to aid child birth.
• In America species of Aristolochiaceae have been used to treat snake bites which lead to one of its common names of Snake Root.
• Aristolochiaceae are fly pollinated which probably led to the evolution of their floral shape.
• The structures of their flowers are similar to the flytrap mechanisms found in the carnivorous genus Nepenthes L. However, whereas Nepenthes digests the insects as a means of adapting to environments with poor soil, Aristolochia and Isotrema simply make use of them for pollination. The flies are attracted by the 'alluring', putridscent of the flowers and pass through the smooth, waxy 'slide zone' on the limb of the flower (Upson & Brett, 2006). At the base of this zone they become trapped in the utricle, an inflated part of the perianth, by the retrorse hairs at its entrance. The insects pollinate the stigmas as they enter the utricle, remaining there until the stamens have ripened and deposited pollen on them as the flower withers. Meanwhile the flies are kept alive with supplies of nectar from trichome nectaries that are usually present in the utricle (Gonzalez, 1994). Most Aristolochia and Isotrema flowers wither after about 24 hours, and as they do so the retrorse hairs that trapped the insects lose their turgidity, releasing them to pollinate more flowers (Petch, 1924).
• Caterpillars of some swallowtail butterfly species and several other species of butterflies feed on the leaves, shoots and flowers of Aristolochia and Isotrema.  The caterpillars can tolerate and sequester the aristolochic acids which are believed to render them poisonous to predators (de Padua et al., 1999).

Number of genera

• Aristolochia (ca. 200 species)
• Isotrema (ca. 15 species)

Status

• Native

Notes on delimitation

• Aristolochiaceae is currently in the order Piperales because it has trimerous flowers, monosulcate or inaperturate pollen and adaxial prophylls. This order of dicotyledons is close to the monoctyledons also because of the trimerous flowers and pollen structure.
• It has been thought to be close to Annonaceae because the flowers have several carpels, oil cells and the well developed petals of Sauruma, although the genera found in Central and South America do not have petals (González, 2000).
• The gynostemium, perianth and inferior ovary with many ovules make it similar to Rafflesiaceae.
• However, this is a distinctly characteristic family. Cronquist considered it to be in a monofamilial order of it's own: Aristolochiales.

Literature

Important literature

De Padua, L.S., Bunyapraphatsara, N. & R.H.M.J. Lemmens. (1999). Plant Resources of South-East Asia 12(1). Medicinal and Poisonous Plants 1. Backhuys Publishers, Leiden.

Feuillet, C. & O. Poncy.1998. Aristolochiaceae. In: A.R.A. Görts-van Rijn & M.J. Jansen Jacobs (eds), Flora of the Guianas 10.

González, F.A. 1990. Aristolochiaceae. Flora de Colombin 12.

González, F.A. 1994. Aristolochiaceae. In: G. Harling & L. Anderson (eds) Flora of Ecuador 51. 1-42.

González, F.A. and D.W. Stevenson. 2000. Perianth development and systematics of Aristolochia. Flora 195: 370-391.

González, F.A. 2004. Aristolochiaceae, In: N. Smith, S. A. Mori, A. Henderson, D. W. Stevenson & S. V. Head (eds.), Flowering Plant of the Neotropics: 31-33. Princeton, Princeton University Press.

Petch, T. (1924). Notes on Aristolochia. Annals of the Royal Botanic Gardens,Peradeniya 8: 1-108.

Pfeifer, H.W. 1970. Taxonomic Revision of the Pentandrous species of Aristolochia. The University of Connecticut Publication Series.

Upson, T. & Brett, R. (2006). 554 Aristolochia cathcartii. Curtis's Botanical Magazine 23; 1:84-90.

Aristolochiaceae, B.L. Stannard. Flora Zambesiaca 9:2. 1997

Morphology General Habit

Perennial herbs or shrubs, erect, scrambling or climbing, sometimes lianes, often with tuberous rhizomes

Morphology Leaves

Leaves alternate, petiolate, exstipulate, simple, entire, sometimes lobed

Morphology Reproductive morphology Flowers

Flowers terminal, axillary or borne on the stem (cauligerous), solitary, fasciculate or in few to many-flowered racemose or cymose inflorescences, hermaphrodite, epigynous, actinomorphic or zygomorphic, with or without bracts

Morphology Reproductive morphology Flowers Calyx

Calyx petaloid, usually enlarged, basally tubular, expanding into a limb above; limb symmetrically 3-lobed, or unilateral and entire or lobed

Morphology Reproductive morphology Flowers Corolla

Petals absent except in Saruma, vestigial in Asarum

Morphology Reproductive morphology Flowers Androecium

Stamens 6–many in 1–2 or more whorls, free or adnate to the stylar column forming agynostemium; anthers 2-thecous with 4 pollen sacs, extrorse, dehiscing longitudinally

Morphology Reproductive morphology Flowers Gynoecium

Ovary inferior, rarely half inferior, 4–6 locular, syncarpous or apocarpous in Saruma, placentas parietal or seemingly axile; ovules numerous, anatropous, in 1–2 vertical series in each locule, horizontal or pendulous; styles connate into a column; stigma 3–many-lobed

Morphology Reproductive morphology Fruits

Fruit a capsule, dehiscing septicidally or irregularly, or more rarely indehiscent

Morphology Reproductive morphology Seeds

Seeds usually many, variously shaped, raphe sometimes thickened and winged; endosperm abundant, embryo minute

Hydnoraceae, Henk Beentje & Quentin Luke. Flora of Tropical East Africa. 2002

Morphology General Habit

Mostly subterranean, leafless, plants without chlorophyll; body rhizome-like with many slender, unbranched, haustorial roots, parasitic on the roots of the host plant

Morphology Reproductive morphology Flowers

Flowers solitary, emerging from the rhizome-like body, hermaphrodite, the lower part subterranean, large, fleshy, with strong smell, beetle-pollinated; perianth tubular, lobed at apex, lobes 3–4(–5), valvate, fleshy; anthers sessile or very shortly stalked, 3–4(–5), inserted on the hypanthium opposite the perianth lobes, extrorse, with elongate many-locular pollen sacs with slits, forming a lobed ring on the hypanthium (Hydnora), or connate anthers forming a dome (>i>Prosopanche), with (>i>Prosopanche) or without staminodes (>i>Hydnora)

Morphology Reproductive morphology Flowers Gynoecium

Carpels 3(–4), ovary 1-locular, inferior, becoming filled with accrescent placentas covered with many ovules; ovules anatropous, unitegmic; stigma sessile, 1–5-lobed

Morphology Reproductive morphology Fruits

Fruit subterranean, fleshy, with woody pericarp; seeds many, minute

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Subterranean holoparasitic herbs with often massive root systems spreading laterally from the host

Morphology Roots

Roots up to 10 cm wide, 4–5-angled, terete or sometimes flattened

Morphology Reproductive morphology Flowers

Flowers large, solitary, 3–5-merous, fleshy, bisexual or unisexual; perianth-lobes valvate in bud, later erect or reflexed, in some species “bait bodies” are present between the inner margins of the lobes, in others an osmophoric (scent-producing) region (“cucullus”) is present

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens basifixed with large many-celled sessile anthers

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary inferior, 1-celled, with numerous infolded, pendent placentas; stigmas sessile with distinct grooves on the surface

Morphology Reproductive morphology Fruits

Fruit fleshy

Morphology Reproductive morphology Seeds

Seeds numerous, minute.

Distribution

Two genera, Prosopanche De Bary with two species in South and Central America, and Hydnora.

Every, J.L.R. (2010). Neotropical Hydnoraceae.

Morphology

Description

Leafless, echlorophyllus, root -parasitic herbs; roots rhizome -like. Flowers from rooting body (frequently semi-subterranean), large, solitary, bisexual , regular, thick, fleshy , brownish, rugoes on outer surface, coloured on innder surface; tepals 3 - 4 , valvate , sepaloid, basally connate ; stamens equal in number and opposite to perianth parts, staminodes 3, alternating with anthers, anthers connate forming a dome or cap with a small central opening; ovary inferior, syncarpous, unilocular, carpels 3-5, ovules numerous in three groups, stigma sessile . Fruit sweet-smelling, coriaceous berry , woody pericarp splitting irregularly. Seeds small and numerous (500 - 90,000).

Distribution

Distribution in the Neotropics

• Semi-arid areas of Brazil, Paraguay, Costa Rica, Tropical Chile and Argentina.

Diagnostic

Distinguishing characters (always present)

• Root-parasitic herbs.
• No chlorophyll present.
• No leaves.
• Bizarre large, thick, fleshy, valvate flowers which emerge from the ground.

Other important characters

• Flower coloured brown on the outside and whitish inside.
• Anthers form a strange-looking dome with a small opening at the top.
• Huge amount of seeds.

Key differences from similar families

Characters lacking from Neotropical Hydnoraceae but present in similar-looking families;

• Apodanthaceae - very small, unisexual flowers.
• Balanophoraceae - fungus-like inflorescence with small numerous flowers.
• Boraginaceae (Lennoa Lex.) - scale leaves, superiorovary.
• Corsicaceae - small alternate leaves, zygomorphic flowers.
• Cytinaceae - spicate infloresecence.
• Mitrastemonaceae - whorl of opposite-decussate leaves and a superiorovary.
• Orobanchaceae - zygomorphic flowers on racemes or spikes.

General Description

Number of genera

• One genus with four species: Prosopancheamericana (R. Br.) Kuntze, P. costaricensis L. D. Gómez,  P. bonacinae Speg and P. caatingicola R. F. Machado & L.P.Queiroz.

Status

• Native.

General notes

• Defined by Lytton J. Musselman as 'The strangest plant in the World!'.

Notes on delimitation

• Currently placed within the Piperales alongside the aquatic Saururaceae, the Piperaceae Lactoridaceae - which are restricted to the Juan Fernandez Islands - and the family Aristolochiaceae (APGIII).

Literature

Important literature

APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. Botanical Journal of the Linnean Society 161(3): 105-121.

Heywood, V.H. 2007. Hydnoraceae. In: V.H. Heywood, R.K. Brummitt, A. Culham and O. Seberg (eds.). P.169. Flowering Plant Families of the World. Royal Botanic Gardens, Kew.

Musselman, L.J. & Visser, L.J. 1986. The strangest plant in the World!. Veld and Flora 71: 109-111.

Musselman, L.J. 2004. Hydnoraceae. In: Smith, N., Mori, S.A., Henderson, A., Stevenson, D.W. and Heald, S.V. (eds.). Flowering Plants of the Neotropics. Pp. 187-188. The New York Botanical Garden, Princeton University Press, Princeton.

Nickrent, D. (accessed Nov 2010). Hydnoraceae. In: Parasitic Plants Connection website.  http://www.parasiticplants.siu.edu/Hydnoraceae/index.html

Nickrent D.L., Blarer A., Qiu Yin-Long, Soltis D.E., Soltis P.S., and Zanis M. 2002. Molecular data place Hydnoraceae with Aristolochiaceae. American Journal of Botany 89:1809-1817.

Stevens, P. F. 2008. Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/

Watson, L. and Dallwitz, M.J. (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version 3rd March 2009. http://delta-intkey.com 

Hydnoraceae, Lytton J. Musselman. Flora Zambesiaca 9:2. 1997

Morphology General Habit

Subterranean parasitic herbs, on roots of shrubs and trees, with a rhizome-like plant-body attached by unbranched haustoria to the host roots, without chlorophyll and leaves

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, produced endogenously from the “rhizome”, large, 3–4(5)-merous; perianth tubular, valvately lobed at the apex

Morphology Reproductive morphology Flowers Androecium

Androecium inserted on the hypanthium, a complex structure composed of numerous fused anthers which form a large undulating ring (or anthers connate and forming a dome in Prosopanche), with numerous elongate bisporangiate pollen sacs

Morphology Reproductive morphology Flowers Gynoecium

Stigma 4-lobed, sessile and cushion-like Ovary inferior, 3–4-carpellate, unilocular, with numerous infolded, pendant accrescent placentas; ovules numerous

Morphology Reproductive morphology Fruits

Fruit a subterranean fleshy berry with a woody pericarp; seeds numerous, minute