454 PLATANACEAE (PLANE TREE FAMILY) 



PLATANACEAE (PLANE TREE FAMILY) 



Trees, with watery juice, alternate palmately-lobed leaves, sheathing stipules, 

 and monoecious flowers in separate and naked spherical heads, destitute of calyx 

 or corolla the fruit merely club-shaped l-seeded nutlets, furnished with a ring 

 of bristly hairs about the base. Only the following genus (of uncertain rela- 

 tionship). 



1. PLAT ANUS [Tourn.] L. SYCAMORE. BUTTONWOOD 



Sterile flowers of numerous stamens, with club-shaped little scales inter- 

 mixed ; filaments very short. Fertile flowers in separate catkins, consisting of 

 inversely pyramidal ovaries mixed with little scales. Style rather lateral, awl- 

 shaped or thread-like, simple. Nutlets coriaceous, small, tawny-hairy below, 

 containing a single orthotropous pendulous seed. Embryo in the axis of thin 

 albumen. Large trees, with the bark deciduous in broad thin brittle plates; 

 dilated base of the petiole inclosing the bud of the next season. (The ancient 

 name, from irXortfj, broad.) 



1. P. occidentalis L. Leaves mostly truncate at base, angularly sinuate- 

 lobed or toothed, the short lobes sharp-pointed ; fertile heads solitary, hanging 

 on a long peduncle. Rich soil, s. Me. to n. Vt., Ont., s. e. Minn., e. Kan., and 

 southw. Our largest, tree, often 2&-40 m. high, with a trunk 2-4.2 m. in 

 diameter. 



ROSACEAE (Ross FAMILY) 



Plants with regular flowers, numerous (rarely few') distinct stamens inserted 

 on the calyx, and 1-many pistils, which are quite distinct, or (in the second 

 tribe) united and combined with the calyx-tube. Ovules (anatropous) l-few in 

 each ovary ; seeds almost always without albumen. Embryo straight, with large 

 and thick cotyledons. Leaves alternate, with stipules, these sometimes caducous, 

 rarely obsolete or wanting. Calyx of 6 (3-8) sepals (the odd one superior), 

 united at the base, often appearing double by a row of bractlets outside. Petals 

 as many as the sepals (rarely wanting), mostly imbricated in the bud, and in- 

 serted with the stamens on the edge of a disk that lines the calyx-tube. Trees, 

 shrubs, or herbs. 



Tribe I. SPIRAEEAE. Ovary superior and not Inclosed in a calyx-like tube ; carpels 1-12, dry at 

 maturity and (in ours) dehiscent, 2-several(rarely l)-seeded. 



* Carpels inflated ; leaves simple, often palmately lobed. 



1. Physocarpus. Stamens on , in several rows. Carpels 2-5, splitting into 2 valves. Seeds with 



hard shining coat. Shrubs. 



* * Carpels not inflated. 

 +- Carpels alternate with (or of a different number from) the sepals or calyx -lobes. 



2. Spiraea. Stamens on the margin of a disk-like expansion of the floral axis. Carpels splitting 



chiefly along the ventral suture. Leaves simple. Shrubs. 



3. Aruncus. Dioecious. Stamens borne on the upper (inner) surface of a disk-like expansion of 



the floral axis. Leaves compound. Herbs. 



+ +- Carpels (normally 5) opposite the 5 sepals or calyx -lobes. 



4. Sorbaria. Petals imbricated in bud. Seeds pendulous. Flowers small, corymbose. 



5. Gillenia. Petals convolute in bud. Seeds ascending. Flowers long-pcduncled. 



Tribe II. PdMEAE. Carpels few, mostly definite (2-5) and usually connate, borne within and 

 adnate to a cup-like or urn-like depression in the enlarged summit of the floral axis (resembling 

 a calyx-tube), the whole united to form a fleshy fruit. Trees and shrubs, with stipules free 

 from the petiole. 



