2o6 



CRASSULACEAE. 



Stamens of the same number as the sepals ; minute herbs. 

 Stamens twice as many as the sepals ; succulent herbs. 

 Flowers 4-5-parted. 



Carpels erect ; flowers often polygamous. 

 Carpels spreading ; flowers perfect. 

 Flowers 6-12-parted. 



Vol. IL 



1. Tillaeastrum. 



2. Rhodiola, 



3. Sedum. 



4. Sempervivum. 



I. TILLAEASTRUM Britton, Bull. N. Y. Bot. Card. 3: i. 1903. 



Minute, mostly glabrous, aquatic or mud-loving succulent herbs, with opposite entire 

 leaves and very small solitary axillary flowers. Calyx 3-5-parted. Petals 3-5, distinct, or 

 united at the base. Stamens 3-5. Carpels 3-5, distinct. Styles short. Ovules usually few. 

 Follicles few-seeded or several-seeded. [Latin, from the affinity of these plants with the 

 genus Tillaea.] 



About 20 species, of wide geographic distribution. Besides the following, another occurs in 

 the western and southern States 



Flowers sessile or short-peduncled. 



Fruiting peduncles as long as the leaves or longer. 



T. aquaticum, 

 T. Vaillantii. 



I. Tillaeastrum aquaticum (L.) Britton. Pigmy-weed. Fig. 2131. 



Tillaea aqualica L. Sp. PI. 128. I753- 

 Tillaea simplex Nutt. Journ. Acad. Phil, i : 114. 181 7. 

 Bidliarda aqualica DC. Prodr. 3: 382. 1828. 



Tilltieastrum aquaticum Britton, Bull. N. Y. Bot. Card. 3: i. 1903. 

 Stems ascending or erect, i'-3' high, glabrous. Leaves 

 linear-oblong, entire, acutish or obtuse at the apex, connate at 

 the base, 2"-3" long, at length shorter than the internodes; 

 flowers sessile or short-peduncled, i" broad; calyx-lobes, petals, 

 stamens and carpels 4, rarely 3, petals greenish, about twice 

 the length of the calyx-lobes; follicles ovoid, longer than the 

 caly.x-lobes, 8-io-seeded. 



Muddy banks of streams, Nova Scotia to Massachusetts and 

 Maryland, Louisiana and Texas, near the coast, Washington to 

 Lower California and Colorado. Stem often rooting at the nodes. 

 Also in Europe and northern Africa. July-Sept. 



2. Tillaeastrum Vaillantii (Willd.) Britton. Vaillant's Pigmy- 

 weed. Fig. 2132. 



Tillaea Vaillantii Willd. Sp. PI. i : 720. 1798. 



Tillaeastrum Vaillantii Britton, Bull. N. Y. Bot. Card. 3: 2. 1903. 



Similar to the preceding species, 4' long or less, the oblong to linear- 

 oblong leaves about 2" long. Fruiting peduncles elongated, becoming as 

 long as the leaves or longer. 



Prince Edward Island ; Nantucket. Europe and northern Africa. Perhaps 

 a race of the preceding species. 



2. RHODIOLA L. Sp. PI. 1035. 1753. 



Fleshy perennial herbs, with erect, mostly simple stems, broad, rather thin dentate or 

 entire leaves and dioecious or polygamous, yellow, greenish or purplish flowers in terminal 

 cymes. Flowers 4-parted or 5-parted. Calyx shorter than the petals. Carpels distinct, erect. 

 Style very short or none. [Greek, rose, referring to the rose-scented roots.] 



About 8 species, natives of the north temperate zone. Besides the following, 4 others occur 

 in western North America and i on Roan Mountain, North Carolina. Type species : Rhodiola 

 rosea L. 



