Parasitic Genera Included: Lauraceae is a large family composed of ca. 50 genera and 3000 species (Rohwer, 1993, In: Kubitzki et al. The Families and Genera of Vascular Plants, II Flowering Plants - Dicotyldedons, Springer-Verlag). Only one genus, Cassytha L. is parasitic, and is composed of ca. 17 species.
Habit: Perennial, twining parasites. Superficially resembling Cuscuta (dodder). Varying in color (seasonally and developmentally) from green to yellow, orange and light brown.
Parasitism: Hemiparasites. Green color (chlorophyll) often more pronounced on younger tissues. Visser (1981) suggested that the host condition may influence the amount of chlorophyll in the parasite tissue, i.e. increased greening on dormant hosts.
Haustoria: Attaching indiscriminately to various herbaceous and woody plants; often forming dense tangles that may overgrow and kill the host.
Stem: Leafless, photosynthetic, bearing essential oils giving the plants a spicy fragrance. Surface densely covered with wax plates and abundant stomata.
Leaves: Inconspicuous, spirally-arranged scales.
Inflorescence: Spikes, heads or racemes.
Plant Sex: Plants hermaphrodite.
Flowers: Bisexual, sessile, protogynous, perianth 6-merous, subtended by a minute bract and two bracteoles. Receptacle shallow but after anthesis becoming deeply urceolate. For here, outer perianth whorl interpreted as three sepals, inner whorl as three petals (otherwise, six tepals).
Calyx: Three sepals, smaller than the petals, resembling the subtending bracts.
Corolla: Three petals, white or whitish in color.
Androecium: 12-merous, composed of nine fertile stamens (in three whorls of three), occassionally 6 with the second or third whorl sterile. Glands present on stamens of the third whorl. The first and second whorl introrsely dehiscent, the third extrorse. The fourth whorl composed of cordate staminodes. Filaments shorter or longer than the anthers, sometimes with lateral outgrowths. Expansion of the filament and connective results in a laminar stamen. Anthers basifixed, 2-locular, dehiscent by uplifting valves. Pollen nonaperturate, ellipsoidal, with four sutures running lengthwise, wall intricately sculptured.
Gynoecium: Composed of one carpel; one locular. Style cylindrical, terminated by a three-parted stigma.
Ovule: Solitary, pendulous. Embryo-sac development Polygonum-type.
Embryo: Well differentiated, achlorophyllous, straight.
Fruit: A drupe, completely enclosed in the accrescent receptacular tube. Drupe white when ripe, drying blackish in C. filiformis but red in C. ciliolata. Tepals persistent as minute remnants on top of fruit.
Seed: Without endosperm, solitary, with hard seed coat. Seeds remain dormant because of the impermeable seed coat, germinating only after softening by microbial action (Visser 1981).
Chromosomes: X = 12.
Link to Family to Description in Delta (Lauraceae)
SIUC / College of Science / Parasitic
Plant Connection / Lauraceae
Last updated: 15-May-06 / dln