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.
Perianth in a single whorl, as a rule, corolla, and frequently calyx absent. Flowers in catkins, or not; ovary superior or inferior; stigmas 2-3, or single.
Order 61. Illecebraceae. - Herbaceous plants; stems branched; leaves entire; stipules membranous; flowers in cymes, bisexual; sepals 4-5, persistent, enclosing fruit; petals small or absent; stamens hypogynous or perigynous; ovary I-celled, free; ovule 1.
Order 62. Amarantaceae. - Herbaceous plants; no stipules; flowers unisexual; perianth 3-5-partite, membranous; stamens 3-5, opposite perianth lobes, hypogynous; ovary I-celled, free; ovule 1; stigmas 3.
Order 63. Chenopodiaceae. - Herbaceous plants; leaves alternate; no stipules or sheaths; flowers 1-2-sexual, with or without bracts, perianth 3-5-partite, persistent; stamens 5 or 3, opposite the perianth lobes; anthers 2-celled; ovary I-locular; 1 ovule; stigmas 2; fruit a utricle enclosed in perianth.
Order 64. Polygonaceae. - Herbaceous plants; leaves alternate, with sheathing membranous stipules (ochreae); flowers bisexual; perianth 5-6-partite, petaloid or not; persistent; stamens 5-8, from base of perianth, opposite the perianth lobes; ovary I-celled, free; styles 1-3; ovule 1, erect; fruit a hard nut.
Order 65. Aristolochiaceae. - Herbaceous plants or shrubs; leaves alternate; no stipules; flowers bisexual, solitary or axillary, regular or irregular; perianth superior, 3-lobed, bell-shaped or trumpet-shaped; stamens 6-12, epigynous; ovary 6-locular; styles 6; ovules many; fruit a capsule or berry.
Order 66. Thymelaeaceae. - Shrubs, evergreen, or deciduous; leaves alternate, entire; without stipules; flowers bisexual; perianth inferior, tubular, petaloid, 4-5-fid; stamens 8, in 2 series; anthers 2-celled; ovary 1-2-celled, free; ovules 1-3, pendulous; fruit a drupe or berry.
Order 67. Elaeagnaceae. - Shrub, deciduous, spinous; plant dioecious; leaves alternate; male flowers in axillary clusters; perianth 2-lobed; stamens 4; female flowers solitary, perianth tubular, style short; stigma long; nut 1-seeded, enclosed in calyx-tube.
Order 68. Loranthaceae. - Shrub, evergreen, parasitic; stem jointed; leaves opposite, without stipules; plant dioecious; flowers small, green; perianth superior, 4-partite; stamens 4, adnate to perianth lobes; anthers sessile; stigma sessile; ovary I-locular; fruit a berry, I-seeded.
Santalaceae. - Herbaceous plants, hemiparasitic on roots; leaves alternate; no stipules; flowers bisexual; solitary, or in cymes or racemes; perianth 5-lobed, persistent, with tuft of hairs on face of lobes, adnate to ovary; stamens 5; filaments short; ovary 1-celled; style short; stigmas 1-5; ovules 2-5, placenta central; fruit I-celled, I-seeded.
Order 70. Euphorbiaceae. - Herbaceous plants or shrubs, with or without milky latex; leaves alternate; stipules present sometimes; flowers 1-2 sexual; perianth lobed or not; male flowers with 1 or more stamens; anthers 2-celled; female flowers with superior 2-3-lobed, 2-3-celled ovary; stigma simple or compound. Capsule 2-3-celled, opening by elastic mechanism; 1-2 seeds in each cell.
Order 71. Ulmaceae. - Trees, deciduous; leaves alternate; stipules soon falling; flowers 2-sexual, not in catkins; perianth inferior, 4-8 cleft, bell-shaped; stamens 4-8 on perianth and opposite lobes; ovary 1-2-celled; ovules solitary; styles 2; fruit a samara.
Order 72. Urticaceae. (Plants monoecious or dioecious as a rule.) - Herbaceous plants, some twining; leaves opposite or alternate, often with stinging hairs; stipules present; flowers I-sexual, male inflorescence in a panicle, female inflorescence in catkins; perianth inferior, 4-5 partite; stamens 4-5; inflexed in bud; on perianth; ovary 1-celled, free; ovules solitary; fruit an achene.
Order 73. Myricaceae. (Plant dioecious or monoecious.) - Shrub, deciduous, aromatic; leaves alternate; no stipules; flowers in axillary catkins; bracts overlapping; stamens 6-8, ovary 1-celled; styles 2; fruit a drupe, with waxy coat.
Order 74. Amentaceae (Cupuliferoe). - Trees or shrubs, deciduous; leaves alternate; with stipules; plants monoecious; bracts forming a 3-5-lobed scale; male flowers in spikes; stamens 2-20; anthers 2-celled; female flowers with calyx adnate to ovary, or absent; ovary inferior, 2-3-locular, ovules 2-6; fruit a nut, winged or not, free or enclosed in cupule.
Order 75. Salicaceae. - Tree or shrubs, deciduous; leaves alternate; with stipules; plants dioecious or monoecious; flowers in catkins, before leaves; bracts simple; no perianth; stamens 1 or 2 or more; ovary 1 -celled, superior; ovules many; placentae parietal; styles 2; stigmas 2; fruit a capsule, 2-valved; seeds many, with tuft of hairs.
Order 76. Empetraceae. - Shrub, heath-like, leaves alternate; no stipules; flowers regular, bisexual or plant dioecious; perianth of 6 scales, hypogynous; stamens 3-4; anthers 2-celled; pollen compound; ovary 3-9-celled; 1 ovule in each cell; fruit a drupe.
Order 77. Ceratophyllaceae. - Aquatic plants, submerged; leaves in whorls, multifid; spinose; no stipules; plants monoecious; flowers axillary; perianth or involucre 8-12 partite; stamens 6-12; ovary 1-celled; ovule 1, pendulous.