MAGNOLIOPHYTA

Plant woody, evergreen; lignans, O-methyl flavonols, dihydroflavonols, non-hydrolysable tannins, quercetin and/or kaempferol +, apigenin and/or luteolin scattered, cyanogenesis via tyrosine pathway, lignins derived from both coniferyl and sinapyl alcohols, with Maüle reaction, nicotinic acid metabolised to trigonelline; root periderm deep-seated [check], trichoblasts 0, origin of epidermis with no clear pattern; stem with 2(+)-layered tunica-corpus construction; secondary thickening + [xylem differentiating internally, phloem externally]; wood fibers and wood parenchyma +; reaction wood adaxial [tension wood], with gelatinous fibres; starch grains simple; primary cell wall mostly with pectic polysaccharides; tracheids +; sieve tubes with companion cells and P proteins, plastids with starch grains alone; nodes unilacunar; stomata paracytic; buds axillary; prophylls [and bracteoles] 2, lateral; leaves alternate, simple, with petiole and lamina [the latter formed from the primordial leaf apex], development of venation acropetal, 2ndary veins pinnate, fine venation reticulate, vein endings free, stipules 0; flowers perfect, haplomorphic, parts spiral [esp. the A], free, numbers unstable, P not differentiated, at least some in 3's, A many, development centripetal, with a single trace, introrse, filaments stout, anther ± embedded in the filament, tetrasporangiate, dithecal, dehiscing by a slit down each theca, with at least outer secondary parietal cells dividing, hypodermal endothecium +, tapetum glandular, binucleate, microsporogenesis ?simultaneous, pollen anasulcate, binucleate at dispersal, trinucleate eventually, endexine compact, nectary 0, G free, several, ascidiate, with postgenital occlusion by secretion, ovules marginal, anatropous, crassinucellate, bitegmic, micropyle endostomal, integuments 2-3 cells thick, archesporium 1-celled, megaspore lacking sporopollenin, embryo sac monosporic, 8-nucleate, stylulus short, stigma ± decurrent, wet [secretory]; P deciduous in fruit; seed exotestal; endosperm cellular [first division oblique, micropylar end initially with a single large cell, chalazal end more actively dividing], copious, oily and/or proteinaceous, embryo small-minute, straight, white, cotyledons 2; paleo AP3 gene +.

Note that the actual level to which many of these features, particularly the more cryptic ones, should be assigned is unclear, because taxa in the basal angiosperm grade have been little studied.

REST:

Pollen with tectum.

REST:

(Neolignans +), ethereal oils in spherical idioblasts [lamina and P ± pellucid-punctate]; vessel elements with scalariform perforations; pollen with a ± columellate ektexine, tectum interrupted, nucellar cap +.

REST:

Carpels plicate, postgenital occlusion by fusion.

EUDICOTS

Myricetin, delphinidin scattered, ethereal oils 0, asarone 0 [unknown in some basal groups and some asterids]; root epidermis derived from root cap [?Buxaceae, etc.]; stomata various; flowers dimerous, cyclic, members of whorls alternating; filaments fairly slender, basifixed, pollen tricolpate, G with complete postgenital fusion; seed coat?

REST:

?

CORE EUDICOTS

Ellagic and gallic acids common, cyanogenesis via phenylalanine, isoleucine or valine pathways; small deletion in the 18S ribosomal DNA common.

REST:

Flowers rather stereotyped: 5-merous, K and C distinct, A = 2x K [secondary polyandry widespread], pollen tricolporate, (nectary disc +), G = K, connate, compitum + [level?], placentation axile, stigma not decurrent; fruit loculicidal when a capsule; endosperm nuclear; small deletion in the 18S ribosomal DNA common[?].

Saxifragales + Vitales + Rosids:  Back to Main Tree

Nodes 3:3.

SAXIFRAGALES Dumortier*  Back to Main Tree

Ellagic acid, myricetin, flavonols +; cuticle waxes as clustered tubules [palmitone the main wax, at least in Paeoniaceae], stomata anomocytic; branching from the previous flush [woody members]; leaf teeth with gland broadening distally and apical foramen, higher order lateral veins joining it, stipules +; anthers basifixed, with basal pit, pollen often other than colporate, floral apex concave early in development [G often (semi-)inferior], carpels free, at least apically, micropyle bistomal, stigmas decurrent, at most slightly wet; seeds ± exotestal; endosperm type?, embryo size?

The teeth are basically rosid, although Cercidiphyllum is described as being ± chloranthoid (not very different), while Hamamelidaceae can have teeth with a clear, glandular apex (fothergilloid) and Altingiaceae are platanoid (basically, the higher order lateral veins do not quite make it to the tooth - Hickey & Wolfe 1975; Tetracarpaea also lacks such veins - Hils et al. 1988). Despite appearances, the floral apex in nearly all taxa studied is concave (Fishbein et al. 2000).

The clade is suggested by molecular phylogenies (e.g. Soltis et al., 1997; Soltis & Soltis, 1997), in addition to sequence similarity, members having i.a. an insertion in common. However, apart from the Crassulaceae/Saxifragaceae clade, relationships are unresolved, and it has been suggested that Saxifragales rapidly diversified into several lineages - a rapid, ancient radiation (Fishbein et al. 2001). Saxifragales includes Hamamelidaceae, a group classically linking the Englerian Amentiferae (usu. dioecious or monoecious woody plants with an ament, or catkin, with small flowers, and sometimes believed to be primitive), to "dicots" with more conventional flowers. However, Hamamelidae, inc. Amentiferae, are now in several bits, of which one is here - see also Fagales, Malpighiales (Salicaceae), Rosales ("Urticales"), etc. (Qiu et al. 1998). A link between woody Saxifragales and Fagles is still often recognised (e.g. Frohne & Jensen 1992). The old woody Saxifragaceae are spread widely through both rosids and asterids (e.g. Morgan & Soltis 1993); most iridoid-negative, herbaceous and/or crassinucellate members remain here. Ironically, three families of Saxifrahgales are reported to have iridoids (how many origins?), the only families outside Asterids with these compounds! Daphniphyllanae, Saxifraganae and Hamamelidanae, in which Takhtajan (1997) placed most of the families in Saxifragales, are all in Hamamelididae.

For information on the hamamelids as it was beginning to be realised that they might have to be split, see Crane and Blackmore (1989). For pollen, see Hideux and Ferguson (1976), Zavada and Dilcher (1986); floral anatomy and morphology, Gaümann (1919), Bensel and Palser (1975a-c), Hufford and Endress (1989), Drinnan et al. (1995), Fishbein et al. (2000); chemistry, Giannasi (1986), Jay (1971); anatomy, Watari (1939), Ramamonjiarisoa (1980), Cutler and Gregory (1998); and for seed coat, Krach (1976).



Includes Altingiaceae, Aphanopetalum, Cercidiphyllaceae, Crassulaceae, Daphniphyllaceae, Grossulariaceae, Haloragaceae, Hamamelidaceae, Iteaceae, Paeoniaceae, Penthoraceae, Pterostemonaceae, Saxifragaceae, Tetracarpaeaceae.

Synonymy: Altingiales Doweld, Cercidiphyllales Reveal*, Crassulales Lindley, Daphniphyllales Cronquist*, Grossulariales Lindley, Haloragales Bromhead*, Hamamelidales Grisebach*, Paeoniales Heinze*, Sedales Reichenbach f. - Daphniphyllanae Takhtajan*, Saxifraganae Reveal*, Hamamelidanae Takhtajan* - Hamamelididae Takhtajan*

Cercidiphyllaceae + Daphniphyllaceae + Hamamelidaceae + Altingiaceae all have valvate anthers with protruding connectives, but there is little evidence that they form a monophyletic group.

CERCIDIPHYLLACEAE Engler*   Back to Saxifragales

Deciduous trees; chalcones, dihydrochalcones +; cork in outer cortex; primary stem with continuous cylinder; prophyll adaxial; leaves usu. opposite, involute, (margins entire), 2ndary veins palmate, stipule adaxial-petiolar; plant dioecious, P 0, floral apex?; staminate "flower": A 16-34 [= several flowers], anthers valvate, connective protruding, pollen colpate, carpellate "flower": G 2-8 [= flowers], each subtended by a bract, suture abaxial, many ovules/carpel, stylulus long; fruit a follicle; seeds winged, chalazal appendage with hair-pin loop vascular bundle, testa undistinguished, exotestal cells enlarged, slightly thickened; endosperm development?, embryo large; n = 19.

1[list]/2. China and Japan. [Photos - Collection]

Fossils have 2-carpellate flowers with the adaxial sutures of the carpels facing each other (Crane & Stockey 1986); the "flowers" of today's species are pseudanthia. Takhtajan (1997) describes the venation of leaves on the long shoots as being pinnate, but the main secondary veins arise within 5(-10) mm of the base. For reported variation in nodal anatomy, see Howard (1979). General information from Endress (1993). Endosperm type?

DAPHNIPHYLLACEAE Müller Argoviensis*   Back to Saxifragales

Evergreen trees or shrubs; plants Al-accumulators, route I iridoids, triterpene [squalene] alkaloids +, myricetin, hydrolysable tannins, ellagic acid 0; pericyclic fibers 0; pits bordered; true tracheids +; stomata paracytic; plant glabrous; leaves spiral, ± flat, stipules 0; plant dioecious, inflorescence racemose, flowers small, floral apex convex, P (0) 2-6, C 0; staminate flower: A 5-12(-24), filaments with 3 traces, anthers valvate, ?basal pit, connective protruding, pollen colpate, carpellate flower: G [2(-4)], placentation apical-axile to parietal, 2 ovules/ carpel, micropyle zig-zag, stylodia short, recurved, stigmas rather massive, with multicellular protrusions, but no papillae; fruit a 1-seeded drupe; seed coat persistent but thin-walled and crushed, or endotegmen tanniniferous, walls thickened; endosperm cellular, perisperm slight?, embryo small; n = 16.

1[list]/10. East Asia to Malesia. [Photo - Fruit]

The pith is at least sometimes septate. There may be staminodes in both staminate and carpellate flowers; for information on the seed, see Bhatnagar and Kapil (1982). Balanopaceae (see Malpighiales) were included in a bigeneric Daphniphyllanae (Takhtajan 1997).

HAMAMELIDACEAE R. Brown*   Back to Saxifragales

Trees or shrubs; (C-glycosylflavones +); cork superficial; (vestured pits +; true tracheids +; nodes 5:5); sclereids common; petiole bundles annular (arcuate); stomata variable; hairs usu. stellate; bud scales + (0); leaves distichous (opposite, spiral), ± conduplicate-flat or -plicate, (margins entire), 2ndary veins palmate, or strong veins at the very base of the lamina (pinnate), stipules cauline; flowers (2-)4-5(-7)-merous; K free to connate, (0), C usu. ribbon-like, adaxially circinate (0), A often = and opposite K (3-many), staminodia opposite C, anthers valvate (with slits), basal pit uncommon, connective prolonged (not), pollen colpate (6-rugate), nectary a disc, staminodial, or on base of C, G [2], usu. ± inferior, 1(-20) apotropous ovules/carpel, outer integument 6-7 cells across (micropyle zig-zag), styluli ± long, stigmas with multicellular protrusions, but no papillae; fruit a loculicidal and septicidal capsule, K often persistent; testa thick, hard, multiplicative, exotestal cells thickened (not), mesotesta of sclerotic cells, hilum large, often discoloration near the hilum; endosperm slight, nuclear (cellular - Parrotiopsis), perisperm +, embryo long; n = 8, 12, 18.

27/82. Tropical to temperate, esp. East Asia to Australia, not South America. [Photos - Collection] [Photo - Flower]

Buds with one bud scale and branches with one prophyll at the very base are common in temperate genera; fertilisation is also often much delayed. Allonia, a fossil from the Campanian in the E. U.S.A., has stamens 2 x K and perhaps a disc adaxial to them (Magallón-Puebla et al. 1996). What is going on with the growth of Exbucklandia?

Some information is taken from Endress (1970, 1993). For the phylogeny of Hamamelidaceae, see Shi et al. (1998), for a classification of Hamamelidoideae, see Li and Bogle (2001), for some distinctive fossils, see Magállon et al. (2001 and refences).

Synonymy: Disanthaceae Nakai, Exbucklandiaceae Reveal & Doweld, Fothergillaceae Nuttall, Parrotiaceae Horaninow, Rhodoleiaceae Nakai

ALTINGIACAEAE Horaninow   Back to Saxifragales

Trees; route I iridoids +; cork superficial; secretory canals in stem; petiole bundles complex; stomata paracytic; bud scales +; leaves spiral, flat, lobes conduplicate, 2ndary veins palmate, stipules on leaf base; plant monoecious, inflorescence ± capitate; P 0; staminate flower: A 4-10, anthers with slits, pollen spherical, polyporate, fine-reticulate, pistillode +; carpellate flower: staminodes 3-10, G [2], unsealed, (semi)inferior, (transverse), 20< apotropous ovules/carpel [only the lower ones fertile], (micropyle endostomal), stigmas decurrent, with multicellular protrusions, but no papillae; fruit a septicidal (and loculicidal) capsule; seeds winged, testa thinner, exotesta lignified or not, mesotesta ± sclerotic, endotestal cells oblong, lignified, endosperm slight, nuclear, embryo long; n = 15, 16.

1/13. E. Mediterranean, East Asia to Malesia, Central America. [Photos - Collection]

The strongly vascularised phyllomes are interior to the staminal whorl and so are staminodia, nectaries or organs sui generis. The orientation of the carpels varies (Bogle 1986). Secretory canals are also reported from Mytilaria (Hamamelidaceae s. str.). The fossil Microaltingia (ca 90 million years bp) has prolate, tricolpate pollen grains with a coarsely reticulate exine, a more or less superior ovary, ovaries with 8 or more ovules per carpel, and perhaps unwinged seeds; it was perhaps pollinated by insects (Zhou et al. 2001). If correctly assigned here, it is yet another fossil with plesiomorphous features (see also Calycanthaceae and Platanaceae),

For information about Hamamelidaceae s.l., see Bogle (1986: floral morphology, etc.), Ferguson (1989), Melikian (1973), Zavada and Dilcher (1986: pollen), Endress (1993) and Shi et al. (2001: phylogeny, only one genus). This and Hamamelidaceae - "micropyle faces upwards"?

PAEONIACEAE Rafinesque   Back to Saxifragales

Herbs to shrubs; iridoids, ethereal oils, flavones +, myricetin and tannins 0; cork?; stem with cortical vascular bundles; vessel elements with simple or scalariform perforations; nodes also 5:5; petiole bundles annular; indumentum 0 (hairs unicellular); leaves spiral, compound, ultimately ternate, ptyxis variable, margin toothed, base broad, stipules 0; flowers large, terminal, with cortical vascular system, K (3-)5(-7), tough, C 5-8(-13), A many, from 5 trunk bundles continuing spiral of C, centrifugal, basal pits?, pollen colporoid, nectary a lobed disc, G (2) 3-5(-15), usu. many ovules/carpel, outer integument 14-20 cells across, nucellar cap +, archesporium multicelled, stigma expanded, rather oblique, sessile, wet; fruit a follicle, K persistent; seeds arillate, testa vascularised, exotestal cells palisade, variously thickened, the hypodermis palisade, lignified, (some mesotesta thickened); endosperm nuclear, embryo minute; n = 5; germination hypogeal.

1[list]/33. N. Temperate, especially East Asia. [Photo - Fruit]

Johri et al. (1992) called the micropyle exostomal, however, the inner integument, too, partly forms the micropyle. The early stages of embryo development are coenocytic; Takhtajan (1988) provides much information on ovules and seeds.

Paeonia was linked with moderate support to the Crassulaceae clade, or, more weakly, with the Crassulaceae + Saxifragaceae cle in some analyses in Fishbein et al. (2001). Paeoniales were included in Ranunculidae (Takhtajan 1997), and a relationship between Paeoniaceae and Ranunculaceae is often suggested (Mabberley [1997] includes Glaucidium [see Ranunculaceae] in Paeoniaceae) because of gross floral similarities, but they differ in the nature of the petals and nectaries and the development of the androecium. Dilleniales, in which Paeoniaceae were placed by Cronquist (1981), have multistaminate and centrifugal androecia, but differ in gynoecial development, nectary morphology, etc.

Crassulaceae + Aphanopetalum + Tetracarpaeaceae + Haloragaceae + Penthoraceae + Saxifragaceae + Iteaceae + Pterostemonaceae + Grossulariaceae: cork superficial; petiole bundle(s) arcuate; cuticle waxes not tubular; ovules apotropous [all?]; K persistent, withered; endosperm cellular.

(Crassulaceae (Tetracarpaeaceae (Haloragaceae + Penthoraceae)) ((Saxifragaceae (Iteaceae + Pterostemonaceae)) Grossulariaceae) - from Morgan & Soltis (1993). Aphanopetalum (ex Cunoniaceae) is to be placed in the former clade.

Crassulaceae + Aphanopetalum + Tetracarpaeaceae + Haloragaceae + Penthoraceae: stem with endodermis; nodes 1:1; stipules 0.

CRASSULACEAE Jaume Saint-Hilaire*   Back to Saxifragales

Succulent herbs to soft-stemmed shrubs, often crassulacean acid metabolism; pyridine alkaloids, flavones, acylated flavonol glycosides +, ellagic acid 0; red pigment common, even in roots; (cork cortical); vessel elements with simple perforations; young stem with separate bundles; (cortical (and medullary) bundles +); nodes also 1:1-3 and 3:3; cuticle waxes very variable; stomata anisocytic; leaves succulent, ptyxis flat to curved, (margins entire); inflorescence cymose, flowers (3-)5(-32)-merous; (hypanthium +), K and C connate to free, A = and opposite or 2 x K (epipetalous), pollen 3-colporate, G 3-10(+), ± free (placentation parietal), opposite C (odd member abaxial - Tillaea), nectaries at base, 1-many ovules/carpel, styles usu. short (style single), stigmas not to moderately capitate; fruit a follicle (abaxial dehiscence in Diamorpha); exotestal cells with outer wall ± thickened, inner pigmented layer +; endosperm development variable, chalazal haustorium +, embryo long; cytologically hideously variable, n = 4-22+.

33[list]/1300-1400. Cosmopolitan, but not Australia or Polynesia, frequently in drier regions. [Photo - Flower]

Crassuloideae

Leaves opposite; A = K, ovules tenuinucellate; testa reticulo-papillose

Crassula (200).

Sedoideae

Leaves spiral (opposite); K connate basally, A 2x K; testa costate (bipapillose).

Sedum (300), Echeveria (150-200). esp. S. Africa.

There have been several origins of sympetaly in Sedoideae ('t Hart et al. 1999).

The wood lacks rays, and the tissues laid down in the course of secondary thickening are distinctive, as are the S-type plastids in the sieve tubes (for the last, see Behnke 1988). The stomata may also be heliocytic, with an additional ring of distinct cells outside a basically aniocytic configuration. Anthocyanin is also found in roots of Saxifragaceae, as well as Melastomataceae, Balsaminaceae, Asteraceae, Droseraceae, and Francoaceae (Krach 1976; Molisch 1928). Hydathodes are common.

Generic limits are unclear, and many genera - some previously placed in different subfamilies, e.g. Sedoideae and Echeverioideae - hybridise (e.g. Uhl 1976; 't Hart et al. 1999); Sedum occurs in 5/7 main lineages of the family (van Ham 1995; van Ham & 't Hart 1998).

Some information is taken from Spongberg (1977); he notes that the endosperm is usually scant, while Mabberley (1997) describes it as being copious. For a general account of the family, see Eggli (2003).

Synonymy: Cotyledonaceae Martynov, Rhodiolaceae Martynov, Sedaceae Adanson, Sempervivaceae Durande, Tillaeaceae Martynov

Aphanopetalum + Tetracarpaeaceae + Penthoraceae + Haloragaceae

APHANOPETALUM   Back to Saxifragales

Viny shrub; chemistry?; pericyclic fibers 0; leaves opposite, leaf teeth with a single vein, stipules looking like teeth; inflorescence cymose or flowers solitary; flowers 4-merous, hypanthium short, C 0 [rudiments visible only when very young], G seminferior, opposite C, 1 apical ovule/carpel, micropyle exo/endostomal, style 4-lobed apically, with four canals; fruit a nut, K persistent; coat?; endosperm development?, embryo size?; n = ?.

1/2. S.E. Australia. [Photo - Flower]

Two small bundles soon diverge from the main leaf trace. The ray parenchyma stores starch. As in Saxifragaceae and Iteaceae, the vascular trace in the petal plane gives a branch to the lateral sepal position, carpel wall and lateral carpel traces, and a stamen trace; the trace in the sepal plane supplies the carpel wall and median carpel bundle and stamen trace.

Some information is taken from Bensel and Palser (1975a) and Dickison et al. (1994).

Tetracarpaeaceae + Penthoraceae + Haloragaceae:

TETRACARPAEACEAE Nakai*   Back to Saxifragales

Evergreen shrub; chemistry?; plant glabrous; no stem endodermis; leaves spiral, petiole short; inflorescence racemose; floral apex convex; flowers 4(-5)-merous, C spatulate, A 4-8, basal pits?, pollen colporate, nectary 0, G 4 (5), opposite C, many ovules/carpel, micropyle?, stigmas sessile, not expanded; fruit a follicle; exotestal cells ± elongated longitudinally, outer walls thickened, no mechanical layer; endosperm development?, embryo size?; n = ?

1/1. Tasmania. [Photo - Habit]

The teeth are perhaps hydathodeal, but there are no water pores. See Hils et al. (1988) for information.

Penthoraceae + Haloragaceae:

PENTHORACEAE Britton*   Back to Saxifragales

Rhizomatous herbs; flavonoids +, flavones, myricetin, non-hydrolysable tannins 0; cork ?; young stem with pseudosiphonostele; endodermoid layer?; pericyclic fibers 0; leaves spiral, supervolute, colleters +; inflorescence cymose, flowers 5-7-merous; hypanthium +, C 0(-7), A 2x K, pollen colporate, G [5-8], half inferior, opposite K, becoming superior, many ovules/carpel, micropyle?, styles submarginal, short, stigma capitate; free part of each carpel basally circumscissile; exotestal cells with outer wall ± thickened, micropylar operculum endostomal, embryo large; n = 8, 9.

1[list]/1-3. East and South East Asia, E. North America. [Photo - Penthorum Inflorescence]

The sepals are unequal in size and the bracts are lateral to the pedicels. There is a much-enlarged but non-dividing micropylar cell in the embryo - cf. Haloragaceae and their haustorial suspensor. Danilova (1996) shows the carpels opposite the calyx; the first two pair of seedling leaves are opposite. See Spongberg (1972), Haskins and Hayden (1987) and Gornall (1998: Saxifragaceae) for information.

HALORAGACEAE R. Brown*   Back to Saxifragales

Aquatic or amphibious (small trees); flavones +, flavonols 0; cork ?; vessel elements with simple perforations; often calcium oxalate crystals in hair-like cortical cells; cuticle waxes 0 (parallel platelets); leaves opposite (spiral), conduplicate-flat, (pinnately compound), colleters +?; plant monoecious (flowers perfect), inflorescence dichasial, cymose or fasciculate, or flowers solitary; flowers small, (3-)4-merous, K valvate, C deciduous (0), A 8 (= and opposite K), (anthers apiculate), basal pits?, pollen trinucleate, colpate or porate, G inferior (sub 1-locular), opposite C or odd member adaxial, 1 (2) pendulous ovules/carpel, hypostase and poorly developed funicular obturator +, stigmas (sessile) capitate or not, dry; fruit nut-like or schizocarpic nutlets, stones 1- or 4-seeded (schizocarpic), K persistent; exotesta (and hypodermal layer) persistent, thin-walled; endosperm + (nuclear), starchy, haustorial suspensor +, embryo long (short); n = 7 (8).

8[list]/145: Myriophyllum (60). World-wide, especially Australia. [Photo - Collection]

See Moody and Les (2001) for relationships within the family, which may have an Australian origin.

Some information is taken from Orchard and Keighery (1993) and Hernández-Castillo and Cevallos-Ferriz (1999); the latter suggest that the fossil Tarahumara sophiae had carpels free from one another but adnate to a hypanthial wall, while its fruit is described as being drupe-like. Corner (1976) describes the endosperm as being starchy. Myriophyllum appears to have endostomal ovules (Batygina et al. 1985). Nodeal anatomy was observed in Haloragis erecta and Laurembergia, ptyxis in the first. Pelargonidin occurs in leaves, as in Saxifragaceae (Doyle & Sogin 1988). Adventitious roots arise between the leaves in Haloragis.

The monotypic Haloragales were placed near Saxifragales by Takhtajan (1997).

Synonymy: Cercodiaceae A.-L. de Jussieu, Myriophyllaceae Schultz-Schultzenstein

Iteaceae + Pterostemonaceae + Grossulariaceae + Saxifragaceae: leaves spiral.

Iteaceae + Pterostemonaceae: C-glycosylflavones +; stipules +; A = and opposite K, placentation axile, micropyle?, style single; fruit septicidal; endosperm sparse, embryo long.

For the chemistry of these families, see Bohm et al. (1999). Pterostemon also has flavones, in this being like other Saxifragales.

ITEACEAE J. Agardh*   Back to Saxifragales

Trees to shrubs; allitol +, flavonols, ellagic acid 0; hairs unicellular; young stem with separate bundles; pith chambered; leaves conduplicate, margins spiny- or gland-toothed, stipules small, on leaf base or adjacent stem; inflorescence axillary, racemose to paniculate, flowers rather small; hypanthium +, C valvate, anthers lacking basal pits, pollen bilateral, 2-porate, ektexine homogeneous, disc or nectary lining hypanthium, G [2] to subinferior, free above, many (unitegmic - Choristylis) ovules/carpel, stigma punctate-lobed, wet; fruit valves often attached by the stigma; exotestal cells with outer walls thickened; (endosperm moderate - Choristylis); n = 11.

2/18. South East Asia to W. Malesia, E. North America, E. and S. Africa. [Photo - Itea Flower]

Choristylis lacks axial parenchyma. The distinctive pollen is known fossil in Europe.

Some information is taken from Spongberg (1972), Bensel and Palser (1975a), Ramamonjiarisoa (1980) and Gornall et al. (1998).

PTEROSTEMONACEAE Small*   Back to Saxifragales

Shrubs; conical to peltate glandular hairs +; vessel elements also with simple perforations; stipules cauline, minute; inflorescence a corymbose cyme; K valvate, A 5, filaments flattened, toothed, anthers with basal pits?, pollen 3-colporate, 5 staminodes opposite C, disc 0, G [5], largely inferior, orientation?, 4-6 ascending ovules/carpel, (± radiating stylodia +), stigma capitate, ?type; K + C persistent in fruit; seed coat?; n = ?

1[list]/3. Mexico.

The pericyclic fibers seem to be weakly developed and the androecium is obdiplostemonous. Similar peltate glandular hairs are known from Grossulariaceae. For information, see Goldberg (1986) and Wilkinson (1994, 1998), but the family is not well known.

Grossulariaceae + Saxifragaceae: G [2-3].

GROSSULARIACEAE de Candolle*   Back to Saxifragales

Shrubs; cork outer cortex/pericyclic; (vessel elements with simple perforations); pericyclic fibers 0; leaves conduplicate-plicate, margins also lobed, 2ndary veins palmate, bases broad, with thin margins (paired prickles at the nodes); inflorescence racemose, flowers (4-)5-merous; hypanthium well developed, nectary at base, C small, open, A = and opposite K, pollen 8-9-porate, tectum complete, , inferior, usu. median, placentation parietal, many ovules/carpel, outer integument ca 4 layers across, style +, ± divided or not, stigma capitate, wet; fruit baccate; seeds hard, arillate, exotestal cells palisade, mucilaginous, endotestal cells crystalliferous, radial and inner walls lignified; endosperm hemicellulosic, (helobial), embryo short; n = 8.

1[list]/150: Ribes. Temperate N. hemisphere, also along the Andes. [Photos - Collection]

Stem collenchyma is well developed.

Some information is taken from Cutler and Gregory (1998).

Synonymy: Ribesiaceae Marquand

SAXIFRAGACEAE Jussieu*   Back to Saxifragales

Largely herbs; hairs (uni-)multiseriate with multicellular glandular head; cork also pericyclic; vessel elements usu. with simple perforations; young stem with separate bundles (pseudosiphonostele); nodes also 1:1 and 3£:3£; petiole bundles also annular (with medullary or adaxial bundles); leaves (opposite), ptyxis variable, (margins entire), 2ndary veins usu. palmate, stipules basal or sub-basal on petiole, persistent, or cauline [Astilbe], or 0, colleters +; flowers (obliquely monosymmetric), (3-10)-merous; hypanthium present or 0, A (3-)5-10 [C 0, A 10 and C 5, A 5, opposite K, common], obdiplostemonous, pollen colpate, colporate, or 6-9-porate, disc + (0), G [-5)] (free), to inferior, orientation variable, placentation parietal to axile, many (unitegmic) ovules/carpel, stigmas spatulate to capitate, wet or dry; fruit a follicle or septicidal capsule; exotestal cells with outer wall (radial walls) ± thickened, inner pigmented layer + (endotegmen thick-walled [Heuchera, Tolmeia]; crystalliferous); endosperm moderate, development variable, embryo medium (large); n = 7(-17); deletion in the rpl2 intron.

Ca 29[list]/630: Saxifraga (350), Micranthes (70), Chrysosplenium (60), Heuchera (50). Mostly N. temperate (S. temperate, tropical mountains). [Photos - Collection]

Saxifragaceae can be confused with Rosaceae (Astilbe [Saxifragaceae] and Aruncus [Rosaceae - Rosales] are particularly similar), but the former quite often have opposite leaves, their carpels are usually two and connate at the base, and their stamens are fewer. The two families are not close.

In at least some species of Saxifraga, and in Astilbe and Rodgersia, the two carpels are oblique, but in the latter two this is associated with inverted floral orientation, the odd K being abaxial. Many other taxa have median carpels, and the family is obdiplostemonous (Eichler 1878; Engler 1930a; Eckert 1966). Short-cycle Puccinia rusts are frequently found on Saxifragaceae. Hydathodes are common.

There are two major clades in Saxifragaceae, Saxifraga s. str. and the Heuchera clade, members of the latter containing the bulk of the floral variation in the family (Soltis et al. 2001). Generic limits are unclear; hybridisation is extensive and there are various combinations of chloroplast and nuclear genomes. For example, the chloroplast genome of Tellima is also found in Mitella (e.g. Soltis et al. 1993). In Saxifraga the diploid chromosome number varies from 8-60. The inflorescence of core Saxifraga often has cauline bracts, however, that of Darmera is scapose, and there are pollen and testa surface differences between the two. Darmera haas only one integument that is 4-6 cells thick (Gornall 1989). Over 50 vascular bundles may enter the petiole base in some taxa!

In the past, "intermediate" genera were kept in Saxifragaceae because the inclusion of more odd genera had little effect on the family description, but if included in Crassulaceae (e.g.) they would greatly affect its description and hence make that family less discrete. Many woody, tenuinucellate and unitegmic members in particular are entirely unrelated. Thus Escallonia, Hydrangea and many other woody taxa are Asterids, while Parnassia is Parnassiaceae-Celastrales (a conclusion in agreement with data from floral anatomy - e.g. Bensel & Palser 1975b, c). However, the unitegmic Darmera is properly to be retained in Saxifragaceae (Gornall 1989). Fehrenbach and Barthlott (1988) included Dichroa (Hydrangeaceae) Francoa, and Vahlia (Geraniales) as well as Penthorum (Penthoraceae) and Saxifragaceae s. str. in their survey of cuticle waxes, but no significant differences were noted.

Some information is taken from Morf (1950) and Spongberg (1972), and anatomical details from Thouvenin (1890) and Gornall (1998).

Synonymy: Pectiantiaceae Rafinesque