CHAPTER IX. 



MACROSCOPIC AND MICROSCOPIC CHARACTERS OF PARENT-STOCKS 



AND HYBRID-STOCKS. 



The laboratory records of the macroscopic and micro- 

 scopic properties of seven sets of parent-stocks and 

 hybrid-stocks compose this chapter. The more important 

 data have been summarized and carried over into Part I, 

 Chapter V, second and third sections of each parent- 

 hybrid set. 



All of these records were made by Miss Margaret 

 Henderson, B.S., M.A. (University of Pennsylvania), 

 who devoted one and a half years of painstaking care to 

 this very tedious work. 



In the pursuit of this investigation the precautionary 

 measures set forth by Macfarlane, and quoted in full in 

 Part I, Chapter I, pages 4 to 7, were very carefully ob- 

 served, excepting in regard to the selection of the plants 

 that are of the same types as those of the parents and the 

 hybrids. It was not only impossible in this research to 

 obtain the actual parents and hybrid, but also to select 

 from the parent-stocks and hybrid-stocks specimens 

 that correspond to the original types the latter not 

 being known even to the growers themselves, or having 

 been placed on record. It was therefore necessary to 

 select specimens that represent as closely as possible the 

 assumed average type in each case. The plants were also 

 selected with care as to age, and each of the several sets 

 of orchids were kept under the same conditions as regards 

 soil, temperature, moisture, and light in the orchid house 

 of the Botanical Department of the University of Penn- 

 sylvania. It was contemplated at the inception of this 

 research to include representatives of a number of genera, 

 and material was obtained in the form of irids, narcissi, 

 lilies, begonias, etc., but circumstances arose that neces- 

 sitated the limitation of this part of the research. More- 

 over, it was contemplated to study coincidently both 

 plant and starch characters, but conditions caused the 

 abandonment of this project, excepting in the case of 

 Cymbidium and Miltonia. 



The microscopic sections were mounted in either 

 water or acetic acid, the same medium being used for the 

 sections of each set of parent-stocks and hybrid-stocks; 

 or, when the sections were to be stained, immersion was 

 always made for the same length of time, and then the 

 specimens mounted in the same medium. 



All of the macroscopic records given are averages of 

 variable numbers of observations, the number depending 

 upon the amount of available material. All of the micro- 

 scopic records are averages, in each case of not less than 

 25 measurements. The magnification was varied to suit 

 conditions, as is noted here and there in the text ; but it 

 was always the same when examining specimens of a 

 given kind from any given set of parent-stocks and 

 hybrid-stock. 



Unfortunately, through an oversight, many charac- 

 ters that appeared to be exactly, or practically exactly, the 

 same in both parent-stocks and hybrid-stocks were disre- 

 garded in the records. Obviously, had these been in- 

 cluded, the figures of the summaries would have been 

 modified, although not to any important degree, at least, 

 in so far as modifying the principles set forth is 

 concerned. 



In the summaries at the ends of the several sections 

 the signs, 9,3, and 9 = 3, mean nearer to the seed 

 parent, nearer to the pollen parent, and as near to one as 

 to the other parent, respectively. 



1. MACROSCOPIC AND MICROSCOPIC CHARACTERS OF 



TpOMffiA COCCINEA, I. QUAMOCLIT, AND I. SLOTERI. 



(Platea 25 to 29, 6ga. 145 to 177. Tables J, 1 to 10; and I, 1 and 



Summaries. Chart F 1.) 



GENERAL DESCRIPTIONS. 



Ipomcca coccinea Linn. (Quamoclit coccinea Mcench.) 

 (seed parent) is described by House (Bull. Torrey Bo- 

 tanical Club, 1909 xxxvi, 599) as follows: 



"Annual, climbing, glabrous; stems several meters long; 

 leaf blades ovate, 3 to 10 cm. long, cordate, acute or acuminate 

 at the apex, usually thin and submembranaceous. pale beneath, 

 entire or somewhat hastate or angularly lobed; petioles as 

 long as the blades or shorter: peduncles about equaling the 

 leaves or longer, few-flowered or sometimes many-flowered; 

 sepals oblong, 4 to 6 mm. long, the outer ones with subulate, 

 infraterminal awns 2 to 5 mm. long; corolla scarlet, white 

 or orange [orange-flowered form studied], the tube 3 to 4 cm. 

 long, slightly enlarged above, the shallowly cup-shaped limb 

 1.5 to 2 cm. broad, 5-angled; caipsules globose, 6 to 7 mm. high. 



Distribution: Type locality: St. Domingo. Circumtropieal. 

 In America north to Florida, Texas, and Arizona. Extended as 

 an escape from cultivation to Pennsylvania, Ohio, Missouri, and 

 Arkansas." 



Ipomtxa quamoclit Linn (Quamoclit quamoclit Brit- 

 ton, Q. vulgaris Choisy, Q. pinnata, Desr.) (pollen pa- 

 rent) is described by House (loc. cit.) : 



" Stems several meters long, glabrous : leaf-blades 2 to 10 

 cm. long, the pinnate segments narrowly linear : petioles shorter 

 than the blades with numerous short leafy branches in their 

 axils appearing stipule-like: peduncles commonly longer than 

 the leaves: pedicels 25 to 30 mm. long, thickened and fleshy at 

 least in the fruit: sepals oblong, obtuse, mucronate, 3 to 5 mm. 

 long: corolla scarlet or white [scarlet-flowered form studied], 

 25 to 35 mm. long, the tube clavate, the limb nearly flat, the 

 short ovate lobes acute: capsules ovoid, 4-celled, 8 to 10 mm. 

 high. 



"Type locality: India. 



"Distribution: Circumtropieal and extended by cultiva- 

 tion and as an escape through the southern United States, 

 north to Virginia and Kansas." 



With Ipomcra sloteri Macfarlane (hybrid), the vine is 

 more vigorous than that of either parent; stem climbing 

 branching, several meters long; loaf blades, dark green, 

 wider and firmer, 5 to 6 cm. long, deeply lobed : petioles 

 shorter than the blade : peduncles longer than the leaves, 

 2 to 5-flowered, flowers very numerous, pedicles slightly 



785 



