GERANIALES Juss. ex Bercht. et J. Presl Berchtold et Presl, Přir. Rostlin: 221. Jan-Apr 1820 [’Geraniae’]
Habit Bisexual (rarely functionally polygamodioecious), evergreen or deciduous trees or shrubs, suffrutices, perennial or annual herbs (rarely trees), often xerophytic stemsucculents or geophytes, often with root- or stem-tubers. Vegetative anatomy Phellogen ab initio usually superficial (subepidermal, sometimes outercortical). Secondary lateral growth normal or absent (rarely anomalous). Vessel elements usually with simple (rarely reticulate) perforation plates; lateral pits usually alternate (rarely scalariform). Imperforate tracheary xylem elements fibre tracheids or libriform fibres with simple or bordered pits, septate or non-septate (also vasicentric tracheids). Wood rays multiseriate, usually heterocellular (occasionally homocellular) or absent. Axial parenchyma usually paratracheal scanty or vasicentric (sometimes apotracheal diffuse), or absent. Sieve tube plastids S type. Nodes usually 3:3, trilacunar with three leaf traces (sometimes 1:1, unilacunar with one trace, rarely 3:5, trilacunar with five traces, or 5–10:5–10, multilacunar with five to ten traces). Medullary parenchyma with starch grains. Calciumoxalate as single prismatic crystals or groups of crystals, raphides, styloids or druses. Trichomes Hairs usually multicellular (sometimes unicellular), uniseriate, simple or branched (rarely stellate); glandular hairs simple or branched, often containing ethereal oils. Leaves Alternate (spiral) or opposite (rarely verticillate), simple or compound, entire or lobed, with conduplicate to plicate ptyxis. Stipules intrapetiolar or interpetiolar (rarely pairwise and lateral, or absent); leaf sheath usually absent. Petiole vascular bundle transection annular. Venation pinnate or palmate, usually brochidodromous or craspedodromous (rarely actinodromous). Stomata usually anomocytic (sometimes paracytic). Cuticular wax crystalloids usually absent (sometimes as rodlets or platelets). Leaflets and lobes usually serrate (sometimes glandular serrate), crenate or sinuate (sometimes entire).
Inflorescence Terminal, axillary or leaf-opposite, corymbose, thyrse, cymose umbel-like or few-flowered (rarely raceme or panicle), or flowers solitary axillary. Floral prophylls (bracteoles) sometimes absent. Flowers Actinomorphic or zygomorphic. Hypanthium present or absent. Usually hypogyny (rarely half epigyny). Sepals (four or) five, with imbricate (often apically valvate, rarely induplicate-valvate) aestivation, free or connate at base. Petals (two to) five (or six; rarely absent), usually with imbricate (sometimes contorted) aestivation, usually clawed, caducous, free. Nectaries (nectariferous glands) five, antesepalous, alternipetalous, alternating with stamens (nectariferous disc rarely lobate, annular, extrastaminal). Disc extrastaminal (sometimes absent). Androecium Stamens usually five or 5+5 (rarely four or 4+4, 10+5, or 5+5+5), obdiplostemonous. Filaments usually connate at base (sometimes free), free from tepals. Anthers usually dorsifixed (sometimes basifixed), usually versatile, tetrasporangiate, usually introrse (rarely extrorse or latrorse), longicidal (dehiscing by longitudinal slits). Tapetum secretory or amoeboid-periplasmodial. Staminodia usually absent (sometimes five, extrastaminal, or three to eight, rarely ten, extrastaminal and alternating with stamens). Pollen grains Microsporogenesis usually simultaneous (rarely successive). Pollen grains (2– )3(–15)-colpate, (2–)3(–15)-colporate or inaperturate (rarely polypantoporate), shed as monads, bicellular or tricellular at dispersal. Exine tectate or semitectate, with columellate infratectum, reticulate, reticulate-striate, or striate, gemmate, echinate or with other types of supratectal processes. Gynoecium Pistil composed of (two to) five (to seven) antepetalous connate carpels. Ovary usually superior (rarely semi-inferior), (bilocular to) quinquelocular, (bilobate to) quinquelobate. Stylodia (four or) five (style sometimes single, simple, or absent). Stigmas (two to) five (sometimes one, capitate or tri- or quinquelobate), punctate to slightly widened, usually papillate (rarely non-papillate), usually Dry (sometimes Wet) type. Pistillodium absent.
Ovules Placentation usually axile (sometimes marginal, rarely apical, basal or intrusively parietal). Ovules usually one or two (rarely up to twelve, only one of which is developing, or up to c. 50) per carpel, usually anatropous to campylotropous by insertion of inner integument (rarely hemianatropous), ascending, pendulous or ascending, usually epitropous, bitegmic (outer integument sometimes mostly epidermal in origin), crassinucellar. Micropyle usually bistomal (sometimes endostomal), often Z-shaped (zigzag). Nucellar cap usually absent (rarely present). Megagametophyte monosporous, Polygonum type. Endosperm development ab initio nuclear. Endosperm haustoria? Embryogenesis onagrad or asterad. Fruit Usually a schizocarp with (four or) five single-seeded (rarely follicular) mericarps (rarely a loculicidal, septicidal or septifragal capsule). Seeds Aril usually absent. Seed coat usually testal-exotegmic (rarely exotestal). Exotesta usually unspecialized (rarely palisade). Endotesta palisade, consisting of malpighian-like cells with calciumoxalate crystals and thickened unlignified cell walls. Exotegmen usually palisade, with sinuous, anticlinal and poorly lignified cell walls. Endotegmen sometimes with slightly lignified cell walls. Perisperm not developed. Endosperm usually absent (sometimes sparse, rarely copious), oily. Embryo straight to curved (rarely spirally twisted), oily, well differentiated, usually with chlorophyll. Cotyledons two. Germination phanerocotylar. Cytology x = 4, 7–15 DNA Plastid gene infA lost/defunct. Mitochondrial intron coxII.i3 lost. Phytochemistry Flavonols (kaempferol, quercetin, myricetin), flavone-C-glycosides, desoxyflavonoids with B-ring, monoterpenoids (citronellol, geraniol) and their esters (citronellyl, geraniyl [pelargonium-oil]), oleanolic acid derivatives, ellagic and gallic acids, ellagitannins (e.g. geraniins), alkaloids, toxic bufadienolides, and tartaric acid present. Nonhydrolyzable tannins, proanthocyanidins, and cyanogenic compounds not found. Systematics Geraniales are sister-group to Myrtales.
A probable topology of Geraniales is [Geraniaceae+[Ledocarpaceae+[Melianthaceae+ Francoaceae]]]. Melianthaceae and Francoaceae share the following potential synapomorphies (Stevens 2001 onwards): leaves spiral, with fairly broad insertion and conduplicate ptyxis; inflorescence terminal, racemose, with sterile bract(s) at apex; absence of floral prophylls (bracteoles); carpels lobate; long style; placentae intrusive; ovules in two rows; micropyle bistomal; endosperm copious; embryo short; and presence of inulin.
Cladogram of Geraniales based on DNA sequence data (Soltis & al. 2007).