This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Petals distinct, rarely absent, not united with the sepals, stamens free, hypogynous.
Order 1. Ranunculaceae. - Herbaceous plants, rarely shrubs or woody, a few climbing. Leaves usually alternate, without stipules. Flowers usually regular, sepals 3-6, sometimes petaloid, petals 5 or more, rarely absent. Stamens many, indefinite (rarely 5); anthers adnate, opening longitudinally; carpels numerous, apocarpous or syn-carpous; fruit aggregate, achenes, follicles, berries; seeds albuminous.
Order 2. Berberidaceae. - Shrubs, leaves transformed into spines, usually without stipules; sepals in 2 series, 3 or 4; petals 3 or 4 or 6 or 8; stamens 4-6, opposite the petals; anthers valvate; carpels 1, I-celled; fruit, drupe or berry; seeds fixed by base or on lateral placenta, albuminous.
Order 3. Nymphaeaceae. - Aquatic plants; stems submerged; leaves floating, peltate; flowers regular; sepals 4-5; petals many, indefinite, on the disk, surrounding the ovary; stamens indefinite; stigma peltate; ovary syncarpous, 10-20-locular; ovules numerous; seeds many, surrounded by an aril.
Order 4. Papaveraceae. - Herbaceous plants; stems with milky juice; leaves alternate, without stipules; flowers regular; sepals 2, soon falling; petals 4; stamens indefinite, distinct; stigmas simple or lobed, sessile; ovary syncarpous, free, I-locular; ovules numerous, on parietal placentae; fruit a capsule; seeds albuminous.
Order 5. Fumariaceae. - Herbaceous plants, slender, often climbing; leaves alternate, pinnatifid with no stipules; flowers irregular; sepals 2, soon falling or wanting; petals 4, one or more spurred below; stamens 2, 3-partite, lateral 1-celled; stigma with one or more points; ovary I-celled, syncarpous, free; ovules on 2 parietal placentae or 1 basal ovule; fruit a capsule or nut; seeds albuminous.
Order 6. Cruciferae. - Herbaceous plants; leaves alternate, with no stipules; flowers regular; sepals 4; petals 4, cruciform; stamens 6 (4 long, 2 short) or 4; stigmas 2, alternate with the placentae; ovary syncarpous; 2 carpels with dividing septum which unites the 2 parietal placentae; valves opposite shorter stamens; fruit a siliqua or silicule, usually dehiscent.
Order 7. Resedaceae. - Herbaceous plants; flowers irregular; sepals 4-8, persistent; petals 4-8, entire or lobed; stamens indefinite (10-24), seated on a I-sided hypogynous disk; ovary syncarpous, I-locular, 3- or 6-lobed; ovules many on 3-6 parietal placentae; fruit, a capsule.
Order 8. Cistaceae. - Herbaceous plants or undershrubs; leaves opposite, entire; stipules small, or wanting; flowers regular, sepals 5, outer 2 smaller, or wanting; petals 5, crumpled in bud, falling; stamens numerous; stigmas 3; style simple; ovary syncarpous, 3-carpellary, I-locular; fruit a capsule, 3-, 5-, or 10-valved.
Order 9. Violaceae. - Herbaceous plants; leaves alternate, with persistent stipules; flowers irregular; sepals 5, overlapping; petals 5, irregular, lower spurred; stamens 5, filaments swollen, connective membranous; stigma hooded; ovary syncarpous, 3-carpellary, I-locular; ovules many, on 3 parietal placentae; fruit a capsule, 3-valved.
Order 10. Polygalaceae. - Herbaceous plants; leaves simple, alternate, without stipules; flowers irregular, in racemes; sepals 5, irregular, overlapping; 2 interior, larger, petaloid; petals 3, unequal, 1 larger, anterior, united to staminal tube; stamens 8, united below in 2 equal bundles; anthers I-celled, opening by apical pores; style 1; ovary syncarpous, 2-carpellary, 2-locular; ovules solitary on axile placentae; fruit a capsule; seeds pendulous, enclosed in an aril below.
Order 11. Frankeniaceae. - Herbaceous, prostrate plants; leaves small, slender, opposite without stipules, the margins turned back, as in Heaths; flowers regular, axillary, small; sepals 4-6; calyx persistent; petals 4-6, clawed, with limb-appendages; stamens 4-6, distinct, 2-celled, opening by apical pores or longitudinally; style simple or 3-fid; ovary syncarpous, 2-5-carpellary, I-locular; placentation parietal; fruit a capsule; seeds numerous, very small.
Order 12. Caryophyllaceae. - Herbaceous plants with swollen nodes, leaves opposite, entire; rarely with stipules; flowers regular, in dichasial cymes; sepals 5 or 4, distinct, or tubular below; petals 5 or 4 clawed, or absent; stamens 10 or 8, or 5 or 4, free or united below; anthers opening longitudinally; stigmas 2-5, sessile, slender; styles 2-5; ovary syncarpous, I-locular; often stalked; ovules on central placenta; fruit a capsule, opening by teeth, or valvular, 1- or 2-5-celled, seeds albuminous.
Order 13. Portulaceae. - Herbaceous plants; leaves succulent, smooth; stipules membranous; flowers regular; sepals 2, or 3-5, united below, overlapping in bud; petals 5, united, or not, below; stamens indefinite, or 3-5; inserted on, or opposite the petals; filaments not united; styles 3; stigmas several; ovary syncarpous, I-celled; ovules 3, placenta central, basal; fruit a capsule, 3-valved.
Order 14. Tamaricaceae. - Evergreen shrub; branches slender, feathery; leaves very small; flowers regular, in racemes; sepals 4-5, persistent, overlapping in bud; petals 4-5, soon withering; stamens 4-5, or 8-10, on margin of disk (peltate); styles 3-4; ovary syncarpous, 3-carpellary; ovules several; fruit a capsule, rarely developed, I-locular, 3-valved; seeds many, crowned with tuft of hairs.
Order 15. Elatinaceae. - Plants aquatic; leaves opposite, stipules very small; flowers regular, very small; sepals 3-4, distinct, or united below; petals 3 4; stamens 6-8, free; styles 3-4; stigmas capitate; ovary syncarpous, 3-4-celled; ovules on axile placentae; fruit a capsule, 3-4-celled, 3-4-valved; seeds many.
Order 16. Hypericaceae. - Herbaceous plants or shrubs; leaves opposite, entire, without stipules, with oil glands; flowers regular, yellow; sepals 5, distinct, persistent, overlapping, with glandular dots; petals 5, twisted in bud; stamens indefinite, in bundles; anthers versatile; styles several, usually distinct; ovary syncarpous, 3-5-locular, ovules on axile placentas; fruit a capsule or berry, dry or fleshy, many-celled, many-valved; seeds small, many.
Order 17. Malvaceae. - Herbaceous plants; leaves alternate; stipules falling; flowers regular, axillary; sepals 5, valvate, persistent; epicalyx of 3-9 segments; petals 5, twisted in bud; stamens many, connected into a tube below; anthers 1-celled, opening transversely, kidney-shaped; styles free above; ovary syncarpous, many-celled; ovules 1 in each cell; fruit a schizocarp, with numerous 1-seeded cocci.
Order 18. Tiliaceae. - Trees, deciduous; leaves alternate; stipules falling; flowers regular, in cymes; flower-stalk adnate to bract; sepals 5, valvate in bud; petals 5; stamens indefinite, distinct or united; anthers 2-celled; style simple; ovary syncarpous, 5-locular; ovules 2 in each cell; fruit a nut, 1-2-seeded.
Order 19. Linaceae. - Herbaceous plants; leaves alternate, small; no stipules; flowers regular; sepals 4-5, persistent, overlapping; petals 4-5, twisted in bud, falling, with a claw; stamens 8 or 10, on a ring; anthers versatile; styles 4-5; stigmas capitate; ovary syncarpous, 4-5-celled; ovules 2 in a cell, on axile placentae; fruit a capsule, tipped with hard base of styles; seeds 1 in each spurious cell.
Order 20. Geraniaceae. - Herbaceous plants; leaves simple, with or without stipules; flowers usually regular; sepals 5, persistent, overlapping; petals 5, with a claw, twisted in bud; stamens 5-10; style 1; ovary syncarpous, 5-locular; fruit, a schizocarp, of 5 cocci, beaked, on stylophore; seeds solitary.