cultivation. In addition, its wide adaptation to different soils and climate has made it one of the principal foods of mankind.

Practicums.

195. STUDY OF THE SPIKE OF WHEAT.-Request each student to report the following, after examining a head of wheat:

1. Number of spikelets in the spike of wheat.

2. Number of flowers in each spikelet.

3. Number of grains in the whole spike.

4. Determine the number and arrange weight of grains occupying first, second, third and fourth place from rachis.

5. Number of empty glumes in a spikelet.

6. Make a sketch of the beak, shoulder and auricle of the empty glume.

7. How does the flowering glume differ from the palea?

8. How is the spikelet attached to the rachis?

9. Draw the rachis.

The spikes of wheat should be laid between pieces of moistened blotting paper for several hours before handing the students, in order to toughen the parts.

196. METHOD OF CROSS-FERTILIZATION.-In order to effect cross-fertilization. the anthers must be removed from all the flowers on the spike, before any of them have shed their pollen. This can best be done when or before the anthers are slightly tinged with yellow. The labor may be reduced by removing all but one or two dozen flowers. If spikelets on the middle portion of the spike are left and only the two lower flowers of the spikelet, more uniformity in the maturation of the flowers will be obtained, as well as more uniformity in other particulars. After carefully removing the unbroken anthers, the emasculated spike may be protected by wrapping about it a piece of tissue paper and tying it above and below. One to two days later the flowers will open, which may be told by adjacent uncovered spikes. Pollen may now be brought from the variety chosen for the male parent and deposited upon the stigmas of the emasculated flowers. The cross-pollinated spike is again covered, and requires no further attention until ripe.

In the upper illustration op

erator is removing spikelets which are not to be crossed. In the lower the flowers are being opened to remove the anthers (after Hays).

197. TYPES OF WHEAT.-To familiarize the student with species and subspecies of wheat, give each a couple of spikes and stems of each of the eight species and subspecies, and have him identify by the use of the following outline adapted from Hackel: 1

Triticum L. Genus. Spikes with rarely aborted spikelets, rachis not articulate in cultivated species; lowest one to four spikelets smaller than the others, awnless, 1 True Grasses, pp. 180-183.

asually sterile. Fertile spikelets inflated or ventricose, two- to five-flowered, fruits one to three. Lowest spikelet closely imbricated; empty glumes broad, one- to many-awned, sometimes a toothed apex; flowering glumes rounded on the back, often navicular, many-nerved, ending in one to several awns; fruit slightly compressed laterally, deeply sulcate, hairy at the apex, free. Embryo with epiblast and three rootlets. Annual. Two poorly defined sections of which one (Ægilops L.) is not cultivated.

Species three.

palea falling into the I. Tr. monococcum.

Section II. Sitopyros. Empty glumes sharply keeled. A. Terminal spikelet usually aborted; mature parts; lateral teeth of empty glume acute. B. Terminal spikelets developed; palea entire; lateral teeth of empty glume obtuse.

I.

2.

a Empty glumes chartaceous, shorter than flowering glume; palea as long as flowering glume.

2. Tr. sativum.

b. Empty glumes sometimes longer than flowering glume, chartaceous, lanceolate; palea of lowest flower half as long as its glume. 3. Tr. polonicum. Tr. monococcum L. Spikes compact, articulate, joints separating, spikelets one-awned, usually only lower flowers maturing fruit. Tr. sativum Lam. Three races.

Rachis articulate at maturity; grain entirely enclosed by glumes, not falling out when threshed.

1*. Spikes loose, almost four-sided when seen from above; empty glumes broadly truncate in front, with very short, obtuse middle tooth; obtusely keeled. a. Tr. sat. spelta. Spikes dense, laterally compressed; empty glumes tapering; middle teeth acute; sharply keeled.

2*

b. Tr. sat. dicoccum.

II. Rachis not articulate at maturity; fruiting glumes somewhat open; grain falls out easily.

C. Tr. sat. tenax

Tr. sat. spelta Hackel. Awned or awnless, hairy or smoothspiked; white, gray, blue, reddish.

с

Always awned. Spikes broader on

two-ranked side, narrower on imbricated side.

Tr. sat. tenax Hackel. Four poorly characterized subraces.

1. Empty glumes distinctly keeled in the upper half, rounded of

only slightly keeled below.

• Spikes long, more or less loose, somewhat dorsally compressed.

2.

I Tr. sat. vulgare.

Spikes short, dense, distinctly four-sided.

I' Tr. sat. compactum.

Empty glumes sharply keeled at the base.

* Fruit short, thick, not compressed, broadly truncate above.

!!! Tr. sat. turgidum.

** Fruit oblong, narrow, laterally compressed, somewhat acuminate. I!!!! Tr. sat. durum.

3 Tr. Polonicum L. A very striking species, with large, compressed, mostly blue-green spikes. Spikelets appearing as if cut off transversely, because the third and fourth flowers scarcely reach to the point of the two lower ones; flowering glumes compressed, navicuJar, many-nerved, awned; fruit 8-12 mm. long.

METHOD OF DESCRIBING WHEAT VARIETIES.

198. HALF GROWN PLANT IN THE FIELD. Each student should be given a printed or typewritten sheet as indicated below and requested to describe two or more varieties of wheat growing in the field by underscoring the adjective which most nearly applies to the condition found.

1. Color: light green; medium green; dark green; light yellowish green; medium yellowish green; dark yellowish green; light gray green; medium gray green; dark gray green.

2. Leaf blade: average length of ten blades

3. Leaf blade: average width of maximum dimensions of ten blades

4. Leaf blade: erect; ascending; drooping.

5. Leaf blade: smooth; rough; downy.

6. Leaf blade: veins prominent; veins not prominent.

7. Leaf blade: end tapering; end wit iles parallel.

8. Leaf sheath: green; green shading to p plc.

9. Ligule: 2.5 mm. long; 2 mm. long: m2. long. 10. Ligule: white; purple.

II.

Auricles: white; green; white with purple tips; purple. 12. Auricles: hairy; partly hairy; smooth.

NOTE: The above practicum and those following are intended to teach a method of describing wheat varieties as first proposed by Cobb and published by Scofield, The student should be referred to The Description of Wheat Varieties, by Carl S. Scofield. U. S. Dept. of Agr., Bu. of Pl. Ind. Bul. 47

199. MATURE PLANT IN THE FIELD. Each student should be given a printed or typewritten sheet as indicated below and requested to describe two or more varieties of wheat growing in the field by underscoring the adjective which most nearly applies to the condition found.

1. Height: average of ten culms to tip of apical gloom, not counting awn,

if any

2. Vigor of plant: strong; medium; weak.

3 Diameter below spike: average of ten cuims

4. Depth of furrows below spike: furrowed; medium; smooth.

5. Upper part of culm: solid; semi-solid; hollow.

6. Wall of culm; thick; medium; thin.

7. Color of culm: light yellow; yellow; purple; bronze.

& Foliage: scanty; medium abundant.

9. Rust: leaves, per cent

10. Smut: loose, per cent

11. Spike: erect; leaning; nodding.

; culms, per cent

; stinking, per cent

12. Spike: beardless; partly bearded; bearded.

13. Shattering: badly; medium; none.

200. MATURE DRIED PLANT IN LABORATORY. Give each student a printed or typewritten sheet as indicated below and request a description of two or more varieties from dried samples by underscoring the adjective which most nearly applies to the condition found. If opportunity to study varieties in the field is lacking, some of the items given in (199) may be included here.

1. Length of spike: average of five spikes from base of lower spikelet to tip of apical flowering glume, not counting awn, if any

2. Compactness of spike: very open; open; medium; compact; crowded. 3. Shape, side view: tapering towards apex; tapering both ways; uniform; clubbed.

4. Shape, end view: square; flattened with spikelet; flattened across spikelet. 5. Sterile spikelets: No.

11. Spikelet: spreading widely; spreading; narrow.

12. Spikelet: number of grains

13. Basal hairs: long; medium; short; wanting: white; brown.

14. Outer glume: light yellow; yellow; bronze; black.

15. Outer glume: hairy; partly hairy; smooth.

16. Width of outer glume: broad; medium; narrow.

17. Length of outer glume: long (as flowering glume); medium; short.

18. Attachment of outer glume to rachilla: firm; medium; weak.

19. Beak of outer glume: long; medium; short.

20. Shoulder of outer glume: broad; medium; narrow: square; sloping; round

201. THE GRAIN. Give each student a printed or typewritten sheet as indicated below and request a description of two or more varieties by underscoring the adjective which most nearly applies to the condition found.

1. Density: very hard; hard; medium; soft; very soft.

2. Appearance of cross-section: very horny; horny; dull; starch.

3. Weight: of 100 average seeds in duplicate (a)

(b)

4. Ratio of length to width: divide length of twenty-five grains by width of twenty-five grains with crease down

5. Shape: straight; curved; pear-shaped.

6. Plumpness: plump; medium; shrivelled.
7. Cheeks: flat; plump; angular.

8. At tip: pointed; blunt.

9. At base: pointed; blunt.

10. Crease: deep; medium; shallow: wide; medium; narrow.

11. Brush: large area; small area: long hairs; short hairs.

12.

Color of grain: light yellow; yellow; clear amber; dull amber; clear red; dull red.

202. CLASSIFICATION OF VARIETIES OF COMMON WHEAT. Take preferably fifty varieties of either spring or winter wheat in sheaf and in grain. A desirable Flan is to have one thousand grains of each variety in glass vials one inch in diameter and six inches high, taking care to have the vials of clear glass and uniform diameter. The difference in the size of grains can be noted at a glance and all other characters as easily observed as in larger samples.

Ar. agronomy laboratory, showing materials ready for the study of varieties of wheat.

The student should note what differences, if any, exist between varieties of the same group as for example in smoothness or hairiness of glumes, and length of straw; and in what cases the varieties are probably synonymous. (89) A written report concerning the best ten varieties as shown by Stations testing varieties in