Question 2: Construct a proper dichotomous key (indented or bracketed format) fo
ID: 219066 • Letter: Q
Question
Question 2:
Construct a proper dichotomous key (indented or bracketed format) for the identification of the following eight taxa: Brassicaceae, Cucurbitaceae, Euphorbiaceae, Fabaceae subfamily Faboideae, Fabaceae subfamily Caesalpinioideae, Malvaceae, Salicaceae, and Violaceae. DO NOT MAKE A FLOW CHART! The characters in each couplet should be chosen carefully to permit unambiguous identification of these taxa. Use ONLY those family diagnostic characters emphasized in class! There are many ways that these characters can be used to construct a key, so everyone’s key should be unique.
Explanation / Answer
-Fruit a silicle (i.e., fruit up to 3 times as long as wide), elliptic or oblong to suborbicular ?or obtriangular in outline, sometimes with a notch or sinus at the base and/or apex
- Fruit a silique (i.e., fruit greater than 3 times as long as wide), narrow-oblong to linear in outline, without a notch or sinus at the base or apex
- Ovary and fruit evidently prickly with narrow prickles, petals shorter than 1 cm; fruit 1.3–6?cm long
- Ovary and fruit smooth, verrucose, or with small prickles in longitudinal stripes; petals 1 cm long or longer; fruit 4–60
-Leaf blades palmately lobed with peltate petioles; stamenswith repeatedly branched filaments; capsules covered with soft prickles
-Leaf blades entire or toothed, but not lobed, with basifixed petioles; stamens with simple filaments; capsuleswithout prickles (though sometimes pubescent)
-Plants woody, trees up to 35 m tall; peduncle of the inflorescence adnate to a conspicuous, elongate bract, stamens pentadelphous; fruit a nut-like drupe
-Plants herbaceous or shrubs to 6 m tall in Hibiscus syriacus; inflorescence without an adnate bract; stamensmonadelphous; fruit a capsule or schizocarp
- Winter buds covered by more than one scale; amentsdrooping; flowers subtended by a cup-like disk, without basalglands, each staminate flower with 5–80 stamens
- Winter buds covered by 1 scale; aments erect to spreading, flowers not subtended by a disk, with 1–4 basalglands, each staminate flower with 1–8 stamens
-Sepals lacking basal auricles; corolla green-white; stamensconnate, forming a sheath that surrounds the carpels, none of them appendaged; leafy-stemmed plants 30–90?(–100)?cm tall
-Sepals with basal auricles; corolla white, yellow, blue to purple, or multicolored (but not green-white); stamens connivent but not fused, the two lower ones with appendages that are prolonged backwards into the nectary spur; scapose or leafy-stemmed plants 2–45?cm tall
TEXA Dichotomous key Brassicaceae-Fruit a silicle (i.e., fruit up to 3 times as long as wide), elliptic or oblong to suborbicular ?or obtriangular in outline, sometimes with a notch or sinus at the base and/or apex
- Fruit a silique (i.e., fruit greater than 3 times as long as wide), narrow-oblong to linear in outline, without a notch or sinus at the base or apex
Cucurbitaceae- Ovary and fruit evidently prickly with narrow prickles, petals shorter than 1 cm; fruit 1.3–6?cm long
- Ovary and fruit smooth, verrucose, or with small prickles in longitudinal stripes; petals 1 cm long or longer; fruit 4–60
Euphorbiaceae-Leaf blades palmately lobed with peltate petioles; stamenswith repeatedly branched filaments; capsules covered with soft prickles
-Leaf blades entire or toothed, but not lobed, with basifixed petioles; stamens with simple filaments; capsuleswithout prickles (though sometimes pubescent)
Fabaceae subfamily Faboideae Plants armed by means of reduced, spine-tipped phyllodes; legume mostly enclosed in the persistent calyx Fabaceae subfamily Caesalpinioideae Vegetative portions of plants unarmed; fruit visible most of its length Malvaceae-Plants woody, trees up to 35 m tall; peduncle of the inflorescence adnate to a conspicuous, elongate bract, stamens pentadelphous; fruit a nut-like drupe
-Plants herbaceous or shrubs to 6 m tall in Hibiscus syriacus; inflorescence without an adnate bract; stamensmonadelphous; fruit a capsule or schizocarp
Salicaceae- Winter buds covered by more than one scale; amentsdrooping; flowers subtended by a cup-like disk, without basalglands, each staminate flower with 5–80 stamens
- Winter buds covered by 1 scale; aments erect to spreading, flowers not subtended by a disk, with 1–4 basalglands, each staminate flower with 1–8 stamens
Violaceae-Sepals lacking basal auricles; corolla green-white; stamensconnate, forming a sheath that surrounds the carpels, none of them appendaged; leafy-stemmed plants 30–90?(–100)?cm tall
-Sepals with basal auricles; corolla white, yellow, blue to purple, or multicolored (but not green-white); stamens connivent but not fused, the two lower ones with appendages that are prolonged backwards into the nectary spur; scapose or leafy-stemmed plants 2–45?cm tall
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