268 



ALSINACEAE 



Family 44. ALSINACEAE. Chickweed Family. 



Herbs with opposite leaves, with or without stipules. Flowers perfect, 

 usually cymose. Sepals 4 or 5, distinct. Petals 4 or 5, clawless, rarely 

 wanting. Stamens twice as many as the sepals or fewer. Gynoecium of 

 2-0 united carpels; ovary partly or completely 2-5-celled; styles 2-5. Fruit 

 a capsule, opening with as many or twice as many valves as carpels. Seed 

 several to many on a central placenta. Embryo curved. 



Stipules wanting. 



Capsule opening with twice as many valves or teeth as there are styles; petals deeply 

 2-cleft. 

 Capsule short, ovate or oblong, opening with usually 6 valves; styles usually 3. 



1. Alsine. 

 Capsule long, cylindric, often curved, opening with usually 10 teeth at the apex; 

 styles usually 5. 2. Cerastium. 



Capsule opening with as many, entire or at length 2-cleft, valves as there are styles; 

 petals entire or merely notched at the apex (except in Arenaria Kingii). 

 Styles fewer tlian the sepals, or rarely of the same number and then opposite 

 them. 

 Flowers with a rather prominent, glandular, 10-lobed disk under the ovary; 



plants fleshy. 3. AMMODEXIA. 



Flowers with no or a very inconspicuous disk; plants scarcely fleshy. 

 Seeds with a basal naembranous appendage (strophiole; at the hylum. 



4. AIOEHRINGIA. 



Seeds not strophiolate. 



Valves of the capsule entire. 5. Alsinopsis. 



Valves of the capsule at last 2-cleft. 6. AREN.UilA. 



Styles as many as the sepals and alternate with them. 7. Sagin.\.. 

 Stipules present. 



Leaves whorled; styles 5. 8. Spergula. 

 Leaves opposite; styles usually 3. 



Styles distinct; sepals not spinulose-tipped. 9. Tiss.\. 



Stigmas sessile; sepals spinulose-tipped. 10. Loeflingia. 



1. ALSINE L. Chickweed, Starwort. 



Annual or perennial herbs, with weak spreading stems and alternate leaves. 

 Flowers usually in open cymes. Sepals 5, rarely 4. Petals 5 or 4, deeply 2- 

 cleft, or rarely wanting. Stamens 10 or fewer, hypogynous. Ovary 1-celled; 

 styles 3, rarely 4 or 5, opposite the sepals, if of the same number. Capsule 

 relatively short, opening by twice as many valves as there are styles. Seeds 

 flattened or globose. [Stellaria L.] 



Plant not viscid. 



Basal leaf-blades spatulate to rhombic-obovate, petioled; plants annual. 

 Leaf-blades all ovate or rhombic-ovate. 



Flowers cymose. 1. A media 



Flowers soUtary in the axils. 18. A. washingloniana. 



Stem-leaves small, lanceolate. 2. A. nitens. 



All leaves sessile. 



Upper bracts at least scarious; perennials with rootstocks. 

 Petals minute or none. 



Leaves oblong-lanceolate; branches of the inflorescence at last reflexed. 



3. A. baicalensis. 

 Leaves linear; branches of the inflorescence ascending. 



4. A. alpestris. 

 Petals equalling or exceeding the sepals. 



Leaves broadest at about the middle, narrowed at the base. 



5. A. longifolia. 

 Leaves broadest near the base. 



Calyx 4—5 mm. long; stem not villous. 



Stem 2-3 dm. high, many-flowered; leaves narrowly lanceolate to 

 nearly linear. 

 Sepals lanceolate, very acute, nearly equaUing the capsule. 



6. A. stricliflora. 

 Sepals ovate or ovate-lanceolate, obtuse or mucronate, scarcely 



more than half as long as the mature capsule; pedicels in 

 fruit spreading. 7. A. longipes. 



Stem 3-15 cm. high, usually 1-3-flowered, rarely 4-G-flowered. 

 Leaves narrowly lanceolate; sepals lanceolate, very acute. 



8. A. laeta. 

 Leaves ovate or ovate-lanceolate; sepals ovate-lanceolate, ob- 1 

 tusish. 9. A. Edwardsii. 



Calyx 2-3 mm. long; stem 1 dm. high or less. 3-10-flowered, usually] 

 villous. 10. A. subvestila. 



