Flora of North America species comparison

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Argemone mexicana

Argemone

Mexican poppy, Mexican prickly-poppy, yellow pricklypoppy

poppy, prickly-poppy
Habit Plants annual. Herbs or subshrubs, annual or perennial, caulescent, glaucous, from transitory or persistent taproots; sap white to orange.
Stems

often branching from base, 2.5-8 dm, unarmed or sparingly prickly.

leafy, branching.
Leaves

blades: surfaces unarmed or sparingly prickly on veins;

proximal lobed 1/2 or more distance to midrib;

distal more shallowly lobed, mostly clasping.

sessile;

basal rosulate, cauline alternate;

blade unlobed or commonly shallowly to deeply 1x-lobed;

margins dentate, each tooth terminated by prickle;

surfaces glaucous, often mottled over veins, unarmed or prickly, glabrous or hispid.
Inflorescences

buds subglobose, body 10-15 × 9-13 mm, unarmed or sparingly prickly;

sepal horns terete, 5-10 mm, unarmed.

terminal, cymose;

bracts present.
Flowers

4-7 cm broad, subtended by 1-2 foliaceous bracts;

petals bright yellow or rarely pale lemon yellow;

stamens 30-50;

filaments yellow;

pistil 4-6-carpellate.

conspicuous, sometimes subtended by foliaceous bracts;

sepals 2 or 3, unarmed or prickly, each with erect, subterminal, hollow horn tipped with prickle;

petals 6, in 2 whorls of 3;

stamens 20-250 or more;

pistil 3-5(-7)-carpellate;

ovary 1-locular;

style short, to 3 mm in fruit;

stigma 3-5(-7)-lobed.
Capsules

oblong to broadly ellipsoid, 25-45 × 12-20 mm (including stigma and excluding prickles when present), unarmed or prickly, longest prickles 6-10 mm.

erect, 3-5(-7)-valved, grooved over sutures, prickly, rarely unarmed, dehiscing from apex ca. 1/3 length, valves separating from framework of vascular elements, to which persistent style and stigma remain attached.
Seeds

1.6-2 mm.

numerous, subglobose, minutely pitted, 1-3 mm, aril present.
x

= 14.
2n

= 28.

Argemone mexicana

Argemone
Phenology Flowering and fruiting spring–fall, or throughout year in tropics.
Habitat Waste places, often a weed of roadsides, dooryards, fallow fields
Elevation 0-1500 m (0-4900 ft)
Distribution
from FNA
AL; CT; FL; GA; IL; IN; KS; LA; MA; MD; MI; MO; NC; NE; NJ; NY; PA; SC; TN; TX; VA; ON; Mexico; Central America; West Indies
[WildflowerSearch map]
[BONAP county map]
from USDA
North America; South America; Hawaii [Introduced in other tropical and temperate regions of the world]
[BONAP county map]
Discussion

Argemone mexicana is probably native to southern Florida as well as the Caribbean islands and has been introduced along the coast of the United States from New England to Texas and, more infrequently, inland. Although it has been reported from Mississippi, no specimens are known. It is widespread in temperate and tropical regions around the world by introduction.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species 32 (15 in the flora).

None of the North American species occurs in South America except for the pantropical weeds Argemone mexicana and, probably, A. ochroleuca. Argemone glauca is endemic to Hawaii. Three suffrutescent, perennial species are known from Mexico in Coahuila (A. fruticosa) and Chihuahua (A. turnerae, A. ownbeyana).

Most herbaceous species can be hybridized, but the F1 plants are sterile when the parents differ in ploidy level. The F2 generation, when achieved, consists mainly of plants of low vigor.

The alkaloids of Argemone have been studied extensively. F. S. Stermitz (1968) has suggested that the species fall into four groups (one with two subgroups) according to their alkaloidal properties, and that these groups coincide to a considerable degree with the informal species alliances suggested by G. B. Ownbey (1958). A full evaluation of the importance of alkaloidal content to Argemone taxonomy and evolution has not been published, but there is little doubt that it is highly significant.

The name Argemone intermedia Sweet (Hort. Brit. ed. 2, 1830) is encountered in several regional and local floras but is of uncertain application.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Petals yellow, golden, or bronze.
→ 2
1. Petals white or pale lavender.
→ 4
2. Stamens 150 or more, filaments red or purplish; flowers 7–12 cm wide; petals bright yellow to golden or bronze.
A. aenea
2. Stamens 20–75, filaments yellow; flowers 3–7 cm broad; petals pale lemon yellow to bright yellow.
→ 3
3. Flower buds subglobose, body length ± equal to breadth; petals mostly bright yellow.
A. mexicana
3. Flower buds oblong, body length 1.5–2 times breadth; petals mostly pale lemon yellow.
A. ochroleuca
4. Leaf surfaces prickly on veins, often also minutely prickly or hispid between veins; stems usually closely prickly.
→ 5
4. Leaf surfaces rarely prickly except on veins or unarmed; stems with widely spaced prickles or almost unarmed (copiously long-prickly in A. arizonica).
→ 9
5. Longest capsular prickles simple, 5–8(–10) mm.
→ 6
5. Longest capsular prickles branched, usually 8–35 mm.
→ 7
6. Distal leaf blades not clasping; leaf surfaces densely crisped-hispid between main veins.
A. hispida
6. Distal leaf blades usually definitely clasping; leaf surfaces variously prickly but not crisped-hispid.
A. munita
7. Longest capsular prickles 15–35 mm.
A. aurantiaca
7. Largest capsular prickles about 8–15 mm.
→ 8
8. Apices of leaf lobes angular, marginal teeth 3 mm or more; flowers usually closely subtended by 1–2 foliaceous bracts.
A. squarrosa
8. Apices of leaf lobes usually definitely rounded, marginal teeth usually less than 1 mm; flowers usually not closely subtended by foliaceous bracts.
A. munita
9. Longest capsular prickles branched, usually 8–35 mm.
→ 10
9. Longest capsular prickles simple, 4–10(–12) mm.
→ 11
10. Longest capsular prickles 15–35 mm.
A. aurantiaca
10. Longest capsular prickles 8–15 mm.
A. squarrosa
11. Prickles (when present) of sepals and sepal horns ascending, or sepals unarmed; blades of proximal leaves often lobed less than 1/2 distance to midrib.
→ 12
11. Prickles (when present) of sepals and sepal horns patent; blades of proximal leaves mostly lobed more than 1/2 distance to midrib.
→ 17
12. Leaf blades thick and leathery; stamens 100–120.
A. corymbosa
12. Leaf blades often succulent, but not leathery; stamens 150 or more.
→ 13
13. Flower buds obovoid or oblong; sepal horns usually flattened adaxially.
→ 14
13. Flower buds usually subglobose, rarely ellipsoid or ellipsoid-oblong; sepal horns terete.
→ 15
14. Flower buds obovoid; surface of sepal horns prickly; blades of proximal leaves lobed ca. 3/4 distance to midrib, apices of lobes angular, marginal teeth prominent.
A. pleiacantha
14. Flower buds oblong; surface of sepal horns unarmed; blades of proximal leaves lobed ca. 1/2 distance to midrib, apices of lobes rounded, marginal teeth very short.
A. munita
15. Distal leaves not evidently clasping; stems with scattered prickles, the longest 7–10 mm.
A. gracilenta
15. Distal leaves clasping; stems with shorter prickles.
→ 16
16. Sepal horns 6–10(–15) mm; flower buds ellipsoid-oblong; capsules narrowly to broadly ellipsoid.
A. polyanthemos
16. Sepal horns 3–6(–10) mm; flower buds subglobose to broadly ellipsoid; capsules oblong to oblong-ellipsoid or narrowly ellipsoid.
A. albiflora
17. Blades of distal leaves usually definitely clasping; blades of proximal leaves lobed ca. 1/2–3/4 distance to midrib.
→ 18
17. Blades of distal leaves not definitely clasping; blades of proximal leaves lobed 4/5 distance to midrib or more.
→ 19
18. Blades of proximal leaves lobed ca. 3/4 distance to midrib, apices of lobes angular.
A. pleiacantha
18. Blades of proximal leaves lobed 1/2 or less distance to midrib, apices of lobes usually rounded.
A. munita
19. Flower buds usually subglobose; sepal horns terete, usually slender, unarmed.
A. gracilenta
19. Flower buds oblong to obovoid or ellipsoid; sepal horns terete or flattened or angular, usually prickly.
→ 20
20. Stems copiously long-prickly, often decumbent, diffusely branched; blades of basal and proximal leaves lobed nearly to midrib, lobe length often 5 times width; sepal horns 12–15 mm.
A. arizonica
20. Stems sparsely to copiously prickly, erect, not diffusely branched; blades of basal and proximal leaves lobed 4/5 distanct to midrib or less, lobes proportionately broader; sepal horns 5–12 mm.
→ 21
21. Flower buds usually oblong-obovoid, rarely subglobose; sepal horns usually flattened adaxially, rarely terete.
A. pleiacantha
21. Flower buds broadly ellipsoid to ellipsoid-oblong; sepal horns terete or angular.
→ 22
22. Stems often closely prickly; capsules narrowly ellipsoid-ovoid; seeds 1.8–2.2 mm.
A. chisosensis
22. Stems not closely prickly; capsules narrowly to broadly ellipsoid; seeds about 1.5 mm.
A. sanguinea
Source FNA vol. 3. FNA vol. 3. Author: Gerald B. Ownbey.
Parent taxa Papaveraceae > Argemone Papaveraceae
Sibling taxa
A. aenea, A. albiflora, A. arizonica, A. aurantiaca, A. chisosensis, A. corymbosa, A. gracilenta, A. hispida, A. munita, A. ochroleuca, A. pleiacantha, A. polyanthemos, A. sanguinea, A. squarrosa
Subordinate taxa
A. aenea, A. albiflora, A. arizonica, A. aurantiaca, A. chisosensis, A. corymbosa, A. gracilenta, A. hispida, A. mexicana, A. munita, A. ochroleuca, A. pleiacantha, A. polyanthemos, A. sanguinea, A. squarrosa
Synonyms A. leiocarpa
Name authority Linnaeus: Sp. Pl. 1: 508. (1753) Linnaeus: Sp. Pl. 1: 508. 175: Gen. Pl. ed. 5, 225. (1754)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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