Neotropical Polygalaceae

Description

Annual or perennial herbs, subshrubs, shrubs, trees or lianas (lianas sometimes with anomalous growth); branches sometimes with short emergences on young shoots (Moutabea Aubl.), or ending in a thorn (some species of Acanthocladus Klotzsch ex Hassk.). Stems sometimes with stalked or sessile glands (extrafloral nectaries) at leaf and inflorescence nodes (sometimes incorrectly called stipules) or on petioles. Stipules absent. Leaves usually alternate, rarely opposite or verticillate, simple, sometimes scaly, needle-like; margins entire. Inflorescences terminal or axillary, usually racemose or variously elaborated panicles, rarely spikes, heads, or of solitary flowers; bracts and bracteoles often present, persistent or caducous. Flowers usually zygomorphic, rarely actinomorphic (Diclidanthera Mart.), bisexual; sepals usually 5, usually distinct, quincuncial, the two inner sepals usually larger and petaloid (wings) but sometimes almost similar to outer sepals; petals (4-)5 (Moutabeae), or 3 (Polygaleae), sometimes apically equipped with a terminal tuft of narrow lobes (crest); androecium with (6-)8(-10) stamens, the filaments generally connate, at least in their lower half, forming a cleft sheath or tube, usually adnate to petals, the anthers basifixed, bi- to tetrasporangiate, usually with a falcate slit forming two apical or subapical pores, or less often forming a marginal or ventral, longitudinal slit; pollen polycolporate; annular nectary often present at base of ovary (possessing or lacking a process) or on staminal sheath (as in Bredemeyera Willd.); ovary superior, carpels 2-8, locules 2 or pseudomonomerous in Polygaleae, 2-8 in Moutabeae; ovules 1 per locule, (sub)apical, pendulous, anatropous, bitegmic. Fruits usually capsules, often with a ± pronounced wing (e.g., Bredemeyera and some species of Polygala L.), sometimes berries (Moutabeae), drupes (e.g. Monnina Ruiz & Pav.), dry and indehiscent (sometimes referred to as wingless samaras), or samaras, the samaras single-winged (Securidaca L.), or double-winged (Pteromonnina B.Eriksen and Ancylotropis B.Eriksen). Seeds 1 per locule, glabrous or pilose, sometimes villous or with a comb of long hairs (e.g. Bredemeyera); an exostome aril (caruncle) sometimes present; endosperm typically abundant.

Notes on delimitation

• DNA-sequences of the trnL-F region and rbcL gene support the monophyly of Polygalaceae as well as its position in the order Fabales.

Distribution in the Neotropics

• Acanthocladus Klotzsch ex Hassk.: distributed in Colombia, Ecuador, Peru, Brazil to Argentina.
• Ancylotropis B.Eriksen: E Brazil.
• Badiera DC.: distributed in West Indies, Central America to Ecuador.
• Barnhartia Gleason: restricted to the Guianas, S Venezuela and Amazonian Brazil.
• Bredemeyera Willd.: distributed from Mexico to temperate parts of Argentina
• Diclidanthera Mart.: distributed in Colombia, Venezuela, Guyana, Brazil, Peru and Bolivia.
• Monnina Ruiz & Pav.: distributed from Mexico to Bolivia.
• Moutabea Aubl.: distributed from Costa Rica to Bolivia.
• Polygala L.: widely distributed in the Neotropics.
• Pteromonnina B.Eriksen: disjunctly distributed between the Andes from Ecuador to Chile and eastern South America from north-eastern Brazil to Argentina. One species with a disjunct range is also distributed (by humans?) in Mexico.
• Securidaca L.: distributed in the West Indies and from Mexico to Paraguay.

Distinguishing characters (always present)

• Simple leaves.
• Stipules absent.
• Flowers hypogynous.
• Pistil with 1 ovule/locule.

Other important characters

• Alternate leaves (opposite in Acanthocladus, whorled in some Polygala).
• Flowers usually zygomorphic; papilionaceous in the vast majority (tribe Polygaleae) with 3 petals and 5 sepals, two of which are larger and petaloid.
• Stamens generally 8, sometimes fewer or up to 10, adnate to the petals.

Key differences from similar families

Species with papilionaceous flowers differ from Leguminosae (=Fabaceae< /A>) subfam. Papilionoideae in having:

• Simple leaves (vs. usually compound).
• A 3-merous corolla with a standard of two petaloid sepals (vs. usually a 5-merous corolla including a standard of one petal).
• One ovule per locule in 2-8 carpellate ovaries (vs. usually several ovules per locule and 1-carpellate ovaries).

Number of genera

11 genera:

• Ancyloptropis: (2 spp.)
• Acanthocladus: (6 spp.)
• Badiera: (10-15 spp.)
• Barnhartia: (1 sp.)
• Bredemeyera: (ca 15 spp.)
• Diclidanthera: (8 spp.)
• Monnina: (ca 150 sp.)
• Moutabea: (8-10 spp.)
• Polygala: (ca 150 spp.)
• Pteromonnina: (ca 30 ssp.)
• Securidaca: (ca 80 sp.)

Useful tips for generic identification

Key to genera of Neotropical Polygalaceae

1. Flowers papilionaceous with a trimerous corolla and two petaloid sepals … 2
1. Flowers not papilionaceous; corolla pentamerous ... 9

2. Fruit dehiscent (capsule) … 3
2. Fruit indehiscent (drupe, samara, etc.) … 6

3. Seeds usually provided with a coma (hairs often as long as the seed), then plant leafless or leaves reduced to minute scales ... Bredemeyera
3. Seeds glabrous or with short hairs … 4

4. Plants herbaceous, sometimes woody; calyx usually persistent; when caducous, the keel of the corolla with a crest or a beak ... Polygala
4. Plants woody; calyx caducous; crest or beak on keel of the corolla absent … 5

5. Leaves opposite, sub-opposite or alternate; branches often spine-tipped; capsule with subglobose locules, woody... Acanthocladus
5. Leaves alternate, branches without spines; capsule laterally compressed, sub-coriaceous... Badiera

6. Fruit juicy ... Monnina
6. Fruit dry, sometimes winged … 7

7. Lianas or shrubs; fruit a unilaterally winged samara ... Securidaca
7. Herbs; fruit unwinged or bilaterally winged … 8

8. Keel apically deeply incised; style curved, apically entire with a tuft of hairs; nectary absent ... Ancylotropis
8. Keel apically emarginate; style geniculate, apically bifid without hairs; nectary unilateral ... Pteromonnina

9. Sepals free; ovary 2-3-locular ... Barnhartia
9. Sepals connate; ovary (2-)4-5(-7)-locular ... 10

10. Flowers distinctly zygomorphic; ovary usually (2-)4(-5)-locular ... Moutabea
10. Flowers actinomorphic or only slightly zygomorphic; ovary 5(-7)-locular ...Diclidanthera

Notable genera and distinguishing features

• Monnina: papilionaceous flowers and drupes.
• Polygala: usually herbaceous and with papilionaceous flowers and capsule.
• Securidaca: papilionaceous flowers and unilaterally winged samaras.

Status

Native.

General notes

The position and circumscription of several genera need to be elucidated and modern revisions of some genera, e.g. Securidaca, are still wanting.

Important literature

Aymard, G.A. Berry, P.E. & Eriksen, B. 2004. Polygalaceae. In: Steyermark, J.A., Berry, P.E., Yatskievych and Holst, B.K. (eds.) Flora of the Venezuelan Guayana, vol. 8. Missouri Botanical Garden, St. Louis.

Bernardi, L. 2000. Consideraciones taxonomicas y fitogeográficas acerca de 10 Polygalae Americanas. Cavanillesia Altera I: 1-456.

Blake, S. 1916. A revision of the genus Polygala in Mexico, Central America and the West Indies. Cambridge, MA: Harvard University Press.

Eriksen, B. 1993. A revision of Monnina subg. Pterocarya (Polygalaceae) in Northwestern South America. University of Gothenburg, Gothenburg, PhD thesis.

Eriksen, B. 1993. Phylogeny of the Polygalaceae and its taxonomic implications. Pl. Syst. Evol. 186: 33-55.

Eriksen, B., Ståhl, B. and Persson, C. 2000. Fam. 216. Polygalaceae. In: G. Harling and L. Andersson (eds). Flora of Ecuador, University of Gothenburg, Gothenburg.

Eriksen, B. and Persson, C. 2006(2007). Polygalaceae, pp. 345-363. In: K. Kubitzki (ed.) The Families and Genera of Vascular Plants vol. IX. Springer-Verlag, Berlin.

Forest, F., Chase, M.W., Persson, C., Crane, P.R. and Hawkings, J.A. 2007. The role of biotic and abiotic factors in evolution of ant dispersal in the milkwort family (Polygalaceae). Evolution 61-7: 1675-1694.

Marques, M. do C. 1980. Revisão das espécies do gênero Bredemeyera Willd. (Polygalaceae) do Brasil. Rodriguésia 67:3-33.

Marques, M. do C. 1996. Securidaca L. (Polygalaceae) do Brasil. Arch. Jard. Bot. Rio de Janeiro 34(1): 7-144.

Persson, C. 2001. Phylogenetic relationships in Polygalaceae based on chloroplast DNA sequences from the trnL-F region. Taxon 50: 763-779.

How to cite

Persson, C. & Eriksen, B. (2009). Neotropical Polygalaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Polygalaceae.htm.